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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Forward Gears
The HF mini lathe hasn't been used since I got the slightly bigger much
older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? |
#2
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In article ,
"Bob La Londe" wrote: The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? I don't know in that particular case, but sometimes it's best to leave the "weak link" weak, so it can protect all the other links, and buy a few spares of it so you can get back running after you break it again. Worth considering, anyway. -- Cats, coffee, chocolate...vices to live by Please don't feed the trolls. Killfile and ignore them so they will go away. |
#3
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Forward Gears
On Friday, March 2, 2012 9:13:56 PM UTC-6, Bob La Londe wrote:
The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? I would hope that there'd be no shortage of people that can make you some gears in this group, but if there isn't shoot me an email if you want some hobbed. |
#4
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Forward Gears
On Fri, 2 Mar 2012 20:13:56 -0700, "Bob La Londe"
wrote: The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? You'll need a dividing head, and involute gear cutter for the diametrical pitch and pressure angle and the approximate number of teeth in your gear. eBay is a good place to shop. With these two tools, its a piece of cake, cut a tooth to depth, rotate head, cut next tooth. You might read "Gear and gear cutting" by Ivan Law to get a good grasp of the subject. You'll need machinery handbook to calculate your depths and blank and rotation values, etc. To replace a plastic gear, I'd use AL. Otherwise, I've made gears out of 4140 and then hardened. I've had one running in my backhoe for ten years now. This is a good basic skill to have. You're sure to be confused at first, but then it will seem easy. Just like learning to ride a bicycle. Karl |
#5
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"Karl Townsend" wrote in message ... On Fri, 2 Mar 2012 20:13:56 -0700, "Bob La Londe" wrote: The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? You'll need a dividing head, I don't have a dividing head, but I did recently fit my little rotary table with a lathe chuck, that is reasonable centered and parallel. Is that "good enough", or do you think a head with dividing plates is a must. and involute gear cutter for the diametrical pitch and pressure angle and the approximate number of teeth in your gear. eBay is a good place to shop. Involute gear cutter? Is that one of those "wheel" type cutters I often see in videos on a horizontal mill being used for gear cutting? With these two tools, its a piece of cake, cut a tooth to depth, rotate head, cut next tooth. You might read "Gear and gear cutting" by Ivan Law to get a good grasp of the subject. You'll need machinery handbook to calculate your depths and blank and rotation values, etc. To replace a plastic gear, I'd use AL. I could certainly cut aluminum. You wouldn't worry about galling in this application? I don't really think of aluminum usually when I think of an interacting mechanical part. As a static or linking part sure, but aluminum to steel with mechanical interaction and friction? Otherwise, I've made gears out of 4140 and then hardened. I've had one running in my backhoe for ten years now. LOL. On the mini lathe they would outlast the entire rest of the machine. This is a good basic skill to have. You're sure to be confused at first, but then it will seem easy. Just like learning to ride a bicycle. I have seen some gears cut with a slitting saw, but I wasn't super comfortable with the process. What do you think? Probably go pretty quick if I went with aluminum. |
#6
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Forward Gears
"Ecnerwal" wrote in message
... In article , "Bob La Londe" wrote: The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? I don't know in that particular case, but sometimes it's best to leave the "weak link" weak, so it can protect all the other links, and buy a few spares of it so you can get back running after you break it again. Worth considering, anyway. Its not at all a bad thought, and I probably won't destroy them all that often anyway. I don't recall exactly what I did, but it seems I did something stupid to destroy them in the first place. Hey. Better to learn on a mini lathe than a real piece of machinery right? -- Cats, coffee, chocolate...vices to live by Please don't feed the trolls. Killfile and ignore them so they will go away. |
#7
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wrote in message
news:23072709.176.1330744907493.JavaMail.geo-discussion-forums@ynjc20... On Friday, March 2, 2012 9:13:56 PM UTC-6, Bob La Londe wrote: The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? I would hope that there'd be no shortage of people that can make you some gears in this group, but if there isn't shoot me an email if you want some hobbed. Wow! Thank you. I appreciate that. If I can't come up with a good solution I may just take you up on that. |
#8
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Forward Gears
"Bob La Londe" wrote in message
... wrote in message news:23072709.176.1330744907493.JavaMail.geo-discussion-forums@ynjc20... On Friday, March 2, 2012 9:13:56 PM UTC-6, Bob La Londe wrote: The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? I would hope that there'd be no shortage of people that can make you some gears in this group, but if there isn't shoot me an email if you want some hobbed. Wow! Thank you. I appreciate that. If I can't come up with a good solution I may just take you up on that. That sounds bad doesn't it? Not sure how to rephrase it, so just take my word it wasn't meant bad. LOL. |
#9
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Forward Gears
On 3/3/2012 2:21 PM, Ecnerwal wrote:
sometimes it's best to leave the "weak link" weak, so it can protect all the other links, and buy a few spares of it so you can get back running after you break it again. That's a good principle, but replacement gears aren't necessarily easy to acquire. Better to have a sacificial key or taper pin I think. It could maybe be incorporated into the new steel gears. Someone used to joke about the $100 gear that stripped to protect the 20 cent key, and the wiring harness that burnt to protect the fuse. |
#10
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Forward Gears
On Fri, 2 Mar 2012 20:13:56 -0700, "Bob La Londe"
wrote: The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? Try Boston Gear works http://www.bostongear.com/products/open/index.html# but you will need to be able to quote the gear specs -- Cheers, John B. |
#11
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Forward Gears
"Bob La Londe" wrote in message ... "Karl Townsend" wrote in message ... On Fri, 2 Mar 2012 20:13:56 -0700, "Bob La Londe" wrote: You might read "Gear and gear cutting" by Ivan Law to get a good grasp of the subject. You'll need machinery handbook to calculate your depths and blank and rotation values, etc. To replace a plastic gear, I'd use AL. I could certainly cut aluminum. You wouldn't worry about galling in this application? I don't really think of aluminum usually when I think of an interacting mechanical part. As a static or linking part sure, but aluminum to steel with mechanical interaction and friction? The gears on the 6" Sears/AA lathe are white metal. On mine the ways were seriously worn from use but the gears are still fine. This aluminum gear has held up well to heavy loading: https://picasaweb.google.com/KB1DAL/...10370886636434 I ground the cutter bit with straight sides and rounded the teeth afterwards with a file. Law's book gives a more accurate way to shape the cutter. This is my fixture to shape a cutter bit more closely to the tooth gap, in this case a 30 degree involute spline on a hydraulic pump shaft. The brass-tipped screw centers the pump shaft tooth space on the slot the bit slides in. https://picasaweb.google.com/KB1DAL/...96150338607922 I ground the bit freehand after marking the face beside the contact areas with a fine-tipped felt pen. For the close fitting I pulled strips of plastic-film sandpaper from the hobby store between the splined shaft and the bit. Bluing didn't stain the smooth surface very well. I think smoke from a candle flame would work better. jsw |
#13
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Forward Gears
"Bob La Londe" wrote in message ... The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? http://www.mcmaster.com/#gears/=gi58j2 |
#14
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Forward Gears
Ecnerwal wrote:
In article , "Bob La Londe" wrote: The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? I don't know in that particular case, but sometimes it's best to leave the "weak link" weak, so it can protect all the other links, and buy a few spares of it so you can get back running after you break it again. Worth considering, anyway. Is anything made with plastic gears worth protecting in the first place? no. |
#15
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Forward Gears
On Mar 2, 8:13*pm, "Bob La Londe" wrote:
The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. *I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. *The I remembered I stripped those little nylon gears. *I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? *I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. *Any suggestions on the approach for that? *Best alloy for reasonable wear? LMS had ALL the gears plus extra pitches last I looked. And like the man said, you need a weak link in the chain, otherwise things could get more expensive than just a stripped gear. They are standard metric module gears, guys were using ones scavanged from laser printers and the like for oddball threads. You must not have looked very hard: http://www.littlemachineshop.com/pro...523&category=1 They also have a spare parts kit with some of the other gears, a belt and some fuses. Stan |
#16
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On 2012-03-03, Karl Townsend wrote:
On Fri, 2 Mar 2012 20:13:56 -0700, "Bob La Londe" wrote: The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? You'll need a dividing head, and involute gear cutter for the diametrical pitch and pressure angle and the approximate number of teeth in your gear. eBay is a good place to shop. With these two tools, its a piece of cake, cut a tooth to depth, rotate head, cut next tooth. Yes -- even easier with a horizontal spindle mill with lever feed, but not bad with a vertical spindle mill. However -- the first trick (aside from getting a dividing head) is finding the proper gear tooth cutter for *your* gear. Given that it is an HF machine, the gear will probably be metric, which here in the US makes both the proper gear tooth cutters, *and* the tools for measuring the gear pitch. IIRC, the pitch is specified in "module" for metric gears, while in either diametrical or circular pitch for inch gears. Of course, it is possible to grind special lathe bits to the shape needed, and mount them in a rotating shaft to take the place of the gear tooth cutter -- but it will be slower since it has only one tooth, while the cutters probably have eight or ten teeth. You might read "Gear and gear cutting" by Ivan Law to get a good grasp of the subject. You'll need machinery handbook to calculate your depths and blank and rotation values, etc. To replace a plastic gear, I'd use AL. Otherwise, I've made gears out of 4140 and then hardened. I've had one running in my backhoe for ten years now. That sounds like a good choice -- with one caveat: *If* it is going to mesh with another aluminum gear, you will have galling (transfer of metal from one gear to the other) at the pressure points. You want unlike metals (e.g. stainless steel meshing with aluminum, or brass, or whatever. Stainless and Aluminum are probably the worst for galling. This is a good basic skill to have. You're sure to be confused at first, but then it will seem easy. Just like learning to ride a bicycle. Right. So far, I've made one gear (and planned others). It was a brass gear to replace a broken plastic one, and I've previously posted the URL documenting that project, but if you are still interested, here it is: http://www.d-and-d.com/PROJECTS/TEK-Gear/index.html Enjoy, DoN. -- Remove oil spill source from e-mail Email: | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- |
#17
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On 2012-03-03, Bob La Londe wrote:
"Karl Townsend" wrote in message ... On Fri, 2 Mar 2012 20:13:56 -0700, "Bob La Londe" wrote: The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a [ ... ] My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? You don't want it *too* strong, or some other part of the machine will die when the load gets too high. You'll need a dividing head, I don't have a dividing head, but I did recently fit my little rotary table with a lathe chuck, that is reasonable centered and parallel. Is that "good enough", or do you think a head with dividing plates is a must. Before I answer that (assuming that your rotary table does not have dividing plates), I have to ask *you* -- how many teeth should the gear have? If is is something like 30 teeth, no problem. Most rotary tables have a 90:1 ratio, so three full turns for each tooth and you are fine. However, if it were say 28 teeth, you need 3.2143 turns per tooth. that is 4 degrees for the full turn, and 0.8572 degrees left over. That is 51' 26" added per tooth. Even if you use a spreadsheet or other program to print out a chart -- how long do you think that you could go before you made a mistake? Now, if you have a dividing plate with 14 (or some integer multiple like 28) holes, that works out right. Set the arms on the plate to allow an extra motion of 3 (for 14), or 6 (for 28) holes. Then reposition the arms after that, so the next division advances the same number of holes, and keep going until you reach the starting point again. (And be careful to remember to turn three full turns before going that extra three or six holes, or you will still be out of line.) *This* is why people use dividing heads for making gears. and involute gear cutter for the diametrical pitch and pressure angle and the approximate number of teeth in your gear. eBay is a good place to shop. Involute gear cutter? Is that one of those "wheel" type cutters I often see in videos on a horizontal mill being used for gear cutting? "Involute" is a term for the math defined shape of the gear tooth, and an involute gear tooth cutter is one which will form close to the precise shape needed. These shapes are so the teeth roll against each other, instead of sliding and wearing. With these two tools, its a piece of cake, cut a tooth to depth, rotate head, cut next tooth. You might read "Gear and gear cutting" by Ivan Law to get a good grasp of the subject. You'll need machinery handbook to calculate your depths and blank and rotation values, etc. To replace a plastic gear, I'd use AL. I could certainly cut aluminum. You wouldn't worry about galling in this application? I don't really think of aluminum usually when I think of an interacting mechanical part. As a static or linking part sure, but aluminum to steel with mechanical interaction and friction? No friction with a proper involute shape -- just rolling friction. But this is for *one* gear made of aluminum meshing with the other original plastic gears. If you have to make two or more gears which must mesh with each other, you want dissimilar metals (unless you are using well lubricated steel or cast iron gears) to avoid galling. Aluminum on steel? Fine! Aluminum on brass? Fine. Brass on steel? Fine. Aluminum on Aluminum? *No*! Otherwise, I've made gears out of 4140 and then hardened. I've had one running in my backhoe for ten years now. LOL. On the mini lathe they would outlast the entire rest of the machine. Almost anything will outlast the rest of the machine. Those plastic gears are made to be the "fuse" -- the weak point which breaks before other more expensive parts break. This is a good basic skill to have. You're sure to be confused at first, but then it will seem easy. Just like learning to ride a bicycle. I have seen some gears cut with a slitting saw, but I wasn't super comfortable with the process. What do you think? Probably go pretty quick if I went with aluminum. A slitting saw? *No*! Not for power transmitting gears. Now, if you were making a really large gear (say 1" between teeth or larger), and had the shape laid out with layout die on the flat, you could use a vertical bandsaw to cut a rough approximation, leaving a little extra metal, and then using a file to take to to final shape. This is the way old machinists made large gears. But your gears are not the right size at all for this. A slitting saw *might* work for the gears used in desktop clocks, which don't handle much torque, and which have the flat gear meshing with a cage of rods one of which goes into a slot at a time. And even with this, you would probably have to file the ends of the teeth in the flat to allow the rods to enter properly. Now -- an involute gear tooth cutter looks a lot like s slitting saw -- until you examine the shape of the teeth. Oh yes -- each involute gear tooth cutter has a different shape, precisely appropriate for a specific number of teeth, and close enough for a number around that value. The larger the number of teeth, the wider the range that is close enough. One end of the set is capable of cutting any tooth count from 135 teeth to a rack gear (infinite number of teeth). However, when the number of teeth gets small, the range is also small. The cutters are marked #1 through #8. If you have to cut two gears of different numbers of teeth, the odds are that you will need two cutters unless you are quite lucky. These different cutters make up for the different angles at which the gear teeth mesh. Good Luck, DoN. -- Remove oil spill source from e-mail Email: | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- |
#18
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"DoN. Nichols" wrote in message
... You'll need a dividing head, I don't have a dividing head, but I did recently fit my little rotary table with a lathe chuck, that is reasonable centered and parallel. Is that "good enough", or do you think a head with dividing plates is a must. Before I answer that (assuming that your rotary table does not have dividing plates), I have to ask *you* -- how many teeth should the gear have? If is is something like 30 teeth, no problem. Most rotary tables have a 90:1 ratio, so three full turns for each tooth and you are fine. However, if it were say 28 teeth, you need 3.2143 turns per tooth. that is 4 degrees for the full turn, and 0.8572 degrees left over. That is 51' 26" added per tooth. Even if you use a spreadsheet or other program to print out a chart -- how long do you think that you could go before you made a mistake? Now, if you have a dividing plate with 14 (or some integer multiple like 28) holes, that works out right. Set the arms on the plate to allow an extra motion of 3 (for 14), or 6 (for 28) holes. Then reposition the arms after that, so the next division advances the same number of holes, and keep going until you reach the starting point again. (And be careful to remember to turn three full turns before going that extra three or six holes, or you will still be out of line.) Well, I probably wouldn't do it quite that way. I'ld do a quick spread sheet. Cell 1 would have the tooth count. Cell 2 would have the formula 360/T with T being the number of teeth. Every cell after would have the formula ((360/T)+PC) with PC being the value in the previous cell. Instead of trying to keep track of the number of turns etc, I would just advance the table rotary table to the value given in the numeric table generated by the spreadsheet and tighten the lock screw. Obviously I would only turn the table in one direction so as to account for backlash in the screw. I could do it on paper almost as easily. It would just take a little longer. 13 Tooth Count 27.692308 +360/A1 55.384615 +(360/$A$1)+B2 83.076923 +(360/$A$1)+B2 110.76923 +(360/$A$1)+B2 138.46154 +(360/$A$1)+B2 166.15385 +(360/$A$1)+B2 193.84615 +(360/$A$1)+B2 221.53846 +(360/$A$1)+B2 249.23077 +(360/$A$1)+B2 276.92308 +(360/$A$1)+B2 304.61538 +(360/$A$1)+B2 332.30769 +(360/$A$1)+B2 360 +(360/$A$1)+B2 13 is only selected for example purposes. You could apply this for any number of teeth. I would have no cumulative error. Just whatever level of accuracy I was capable of with the table. *This* is why people use dividing heads for making gears. and involute gear cutter for the diametrical pitch and pressure angle and the approximate number of teeth in your gear. eBay is a good place to shop. Involute gear cutter? Is that one of those "wheel" type cutters I often see in videos on a horizontal mill being used for gear cutting? "Involute" is a term for the math defined shape of the gear tooth, and an involute gear tooth cutter is one which will form close to the precise shape needed. These shapes are so the teeth roll against each other, instead of sliding and wearing. With these two tools, its a piece of cake, cut a tooth to depth, rotate head, cut next tooth. You might read "Gear and gear cutting" by Ivan Law to get a good grasp of the subject. You'll need machinery handbook to calculate your depths and blank and rotation values, etc. To replace a plastic gear, I'd use AL. I could certainly cut aluminum. You wouldn't worry about galling in this application? I don't really think of aluminum usually when I think of an interacting mechanical part. As a static or linking part sure, but aluminum to steel with mechanical interaction and friction? No friction with a proper involute shape -- just rolling friction. But this is for *one* gear made of aluminum meshing with the other original plastic gears. If you have to make two or more gears which must mesh with each other, you want dissimilar metals (unless you are using well lubricated steel or cast iron gears) to avoid galling. Aluminum on steel? Fine! Aluminum on brass? Fine. Brass on steel? Fine. Aluminum on Aluminum? *No*! Otherwise, I've made gears out of 4140 and then hardened. I've had one running in my backhoe for ten years now. LOL. On the mini lathe they would outlast the entire rest of the machine. Almost anything will outlast the rest of the machine. Those plastic gears are made to be the "fuse" -- the weak point which breaks before other more expensive parts break. This is a good basic skill to have. You're sure to be confused at first, but then it will seem easy. Just like learning to ride a bicycle. I have seen some gears cut with a slitting saw, but I wasn't super comfortable with the process. What do you think? Probably go pretty quick if I went with aluminum. A slitting saw? *No*! Not for power transmitting gears. Now, if you were making a really large gear (say 1" between teeth or larger), and had the shape laid out with layout die on the flat, you could use a vertical bandsaw to cut a rough approximation, leaving a little extra metal, and then using a file to take to to final shape. This is the way old machinists made large gears. But your gears are not the right size at all for this. A slitting saw *might* work for the gears used in desktop clocks, which don't handle much torque, and which have the flat gear meshing with a cage of rods one of which goes into a slot at a time. And even with this, you would probably have to file the ends of the teeth in the flat to allow the rods to enter properly. Now -- an involute gear tooth cutter looks a lot like s slitting saw -- until you examine the shape of the teeth. Oh yes -- each involute gear tooth cutter has a different shape, precisely appropriate for a specific number of teeth, and close enough for a number around that value. The larger the number of teeth, the wider the range that is close enough. One end of the set is capable of cutting any tooth count from 135 teeth to a rack gear (infinite number of teeth). However, when the number of teeth gets small, the range is also small. The cutters are marked #1 through #8. If you have to cut two gears of different numbers of teeth, the odds are that you will need two cutters unless you are quite lucky. These different cutters make up for the different angles at which the gear teeth mesh. Good Luck, DoN. -- Remove oil spill source from e-mail Email: | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- |
#19
Posted to rec.crafts.metalworking
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Forward Gears
"Stanley Schaefer" wrote in message
... On Mar 2, 8:13 pm, "Bob La Londe" wrote: The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? LMS had ALL the gears plus extra pitches last I looked. And like the man said, you need a weak link in the chain, otherwise things could get more expensive than just a stripped gear. They are standard metric module gears, guys were using ones scavanged from laser printers and the like for oddball threads. You must not have looked very hard: http://www.littlemachineshop.com/pro...523&category=1 They also have a spare parts kit with some of the other gears, a belt and some fuses. Stan Well, I guess I need to look a little further than that link as well. It doesn't include the 20 tooth reverse gear or 25 tooth forward gear. Neither does the spare parts kit found he http://www.littlemachineshop.com/pro...1223&category= This set does, but it is the only one I could find that does. http://www.littlemachineshop.com/pro...3446&category= Its not a bad option if I used the mill more. 2 yards is a bit steep for basically one gear though. Ah... here we go: http://www.littlemachineshop.com/pro...3455&category= and http://littlemachineshop.com/product...p?critFast=25t Thanks Stanley. I was all prepared to be ****y about your comment, but it lead to a cheap solution without setting up to cut gears. Thank you. I may cut some gears anyway just for the experience, but... |
#20
Posted to rec.crafts.metalworking
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Forward Gears
Well, I probably wouldn't do it quite that way. I'ld do a quick spread sheet. Cell 1 would have the tooth count. Cell 2 would have the formula 360/T with T being the number of teeth. Every cell after would have the formula ((360/T)+PC) with PC being the value in the previous cell. Instead of trying to keep track of the number of turns etc, I would just advance the table rotary table to the value given in the numeric table generated by the spreadsheet and tighten the lock screw. Obviously I would only turn the table in one direction so as to account for backlash in the screw. I could do it on paper almost as easily. It would just take a little longer. Sounds like a case of ingenuity overcoming adversity. Go for it. Or you could put a servo or stepper motor on it. Then you got a CNC 4rth axis. I set mine up that way. Karl |
#21
Posted to rec.crafts.metalworking
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Forward Gears
On Sun, 4 Mar 2012 13:46:27 -0700, "Bob La Londe"
wrote: "Stanley Schaefer" wrote in message ... On Mar 2, 8:13 pm, "Bob La Londe" wrote: The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? LMS had ALL the gears plus extra pitches last I looked. And like the man said, you need a weak link in the chain, otherwise things could get more expensive than just a stripped gear. They are standard metric module gears, guys were using ones scavanged from laser printers and the like for oddball threads. You must not have looked very hard: http://www.littlemachineshop.com/pro...523&category=1 They also have a spare parts kit with some of the other gears, a belt and some fuses. Stan Well, I guess I need to look a little further than that link as well. It doesn't include the 20 tooth reverse gear or 25 tooth forward gear. Neither does the spare parts kit found he http://www.littlemachineshop.com/pro...1223&category= This set does, but it is the only one I could find that does. http://www.littlemachineshop.com/pro...3446&category= Its not a bad option if I used the mill more. 2 yards is a bit steep for basically one gear though. Ah... here we go: http://www.littlemachineshop.com/pro...3455&category= and http://littlemachineshop.com/product...p?critFast=25t Thanks Stanley. I was all prepared to be ****y about your comment, but it lead to a cheap solution without setting up to cut gears. Thank you. I may cut some gears anyway just for the experience, but... you'd spend more on the involute cutter. But this is a needed skill if you got time. Karl |
#22
Posted to rec.crafts.metalworking
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Forward Gears
"Karl Townsend" wrote in message
... Well, I probably wouldn't do it quite that way. I'ld do a quick spread sheet. Cell 1 would have the tooth count. Cell 2 would have the formula 360/T with T being the number of teeth. Every cell after would have the formula ((360/T)+PC) with PC being the value in the previous cell. Instead of trying to keep track of the number of turns etc, I would just advance the table rotary table to the value given in the numeric table generated by the spreadsheet and tighten the lock screw. Obviously I would only turn the table in one direction so as to account for backlash in the screw. I could do it on paper almost as easily. It would just take a little longer. Sounds like a case of ingenuity overcoming adversity. Go for it. Or you could put a servo or stepper motor on it. Then you got a CNC 4rth axis. I set mine up that way. Karl When I mounted the chuck on the table it was my intention to convert it to CNC eventually. Both of my little machine controllers have an unused 4th port. Its would just be a matter of making a mount and adding a motor. The problem I see is that the drive screw for this rotary table has too much back lash in it. I have not looked yet to see if there is anything I can do about it, but I was thinking it might be easier to just make a spindle for a 4th axis. I was thinking I would like something with a much bigger bore than the average lathe spindle or rotary table. If I keep it under 3000 RPM there are some pretty big bore bearings out there. |
#23
Posted to rec.crafts.metalworking
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Forward Gears
"Karl Townsend" wrote in message
... On Sun, 4 Mar 2012 13:46:27 -0700, "Bob La Londe" wrote: "Stanley Schaefer" wrote in message ... On Mar 2, 8:13 pm, "Bob La Londe" wrote: The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? LMS had ALL the gears plus extra pitches last I looked. And like the man said, you need a weak link in the chain, otherwise things could get more expensive than just a stripped gear. They are standard metric module gears, guys were using ones scavanged from laser printers and the like for oddball threads. You must not have looked very hard: http://www.littlemachineshop.com/pro...523&category=1 They also have a spare parts kit with some of the other gears, a belt and some fuses. Stan Well, I guess I need to look a little further than that link as well. It doesn't include the 20 tooth reverse gear or 25 tooth forward gear. Neither does the spare parts kit found he http://www.littlemachineshop.com/pro...1223&category= This set does, but it is the only one I could find that does. http://www.littlemachineshop.com/pro...3446&category= Its not a bad option if I used the mill more. 2 yards is a bit steep for basically one gear though. Ah... here we go: http://www.littlemachineshop.com/pro...3455&category= and http://littlemachineshop.com/product...p?critFast=25t Thanks Stanley. I was all prepared to be ****y about your comment, but it lead to a cheap solution without setting up to cut gears. Thank you. I may cut some gears anyway just for the experience, but... you'd spend more on the involute cutter. But this is a needed skill if you got time. I either have the time or the money, but never both at once. Actually I was looking at some of the lathe turned gear cutters. http://www.youtube.com/watch?v=8UBxNPbg0ls He talks a lot, but it's a good example of what I was thinking of. Maybe an oil hardening drill rod to make the cutter. I don't know, but this little adventure got me reading all kinds of new stuff. |
#24
Posted to rec.crafts.metalworking
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Forward Gears
In article ,
"Bob La Londe" wrote: When I mounted the chuck on the table it was my intention to convert it to CNC eventually. Both of my little machine controllers have an unused 4th port. Its would just be a matter of making a mount and adding a motor. The problem I see is that the drive screw for this rotary table has too much back lash in it. I have not looked yet to see if there is anything I can do about it, but I was thinking it might be easier to just make a spindle for a 4th axis. I was thinking I would like something with a much bigger bore than the average lathe spindle or rotary table. If I keep it under 3000 RPM there are some pretty big bore bearings out there. With good programming, lash (at least consistent lash - and with fancy enough programming, I suppose arbitrary lash) is as little an issue as your ability to measure it - just tell the drive to compensate, and have some sort of homing routine so it has a known point to start compensating from. There's also the simple approach, which is to always rotate the same direction - just as you were planning to do by hand. If you need to be CCW 1 degree, go CW 359 degrees (or vice versa) -- Cats, coffee, chocolate...vices to live by Please don't feed the trolls. Killfile and ignore them so they will go away. |
#25
Posted to rec.crafts.metalworking
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Forward Gears
"Ecnerwal" wrote in message ... In article , "Bob La Londe" wrote: When I mounted the chuck on the table it was my intention to convert it to CNC eventually. Both of my little machine controllers have an unused 4th port. Its would just be a matter of making a mount and adding a motor. The problem I see is that the drive screw for this rotary table has too much back lash in it. I have not looked yet to see if there is anything I can do about it, but I was thinking it might be easier to just make a spindle for a 4th axis. I was thinking I would like something with a much bigger bore than the average lathe spindle or rotary table. If I keep it under 3000 RPM there are some pretty big bore bearings out there. With good programming, lash (at least consistent lash - and with fancy enough programming, I suppose arbitrary lash) is as little an issue as your ability to measure it - just tell the drive to compensate, and have some sort of homing routine so it has a known point to start compensating from. There's also the simple approach, which is to always rotate the same direction - just as you were planning to do by hand. If you need to be CCW 1 degree, go CW 359 degrees (or vice versa) Yeah, I thought of that too. I still want a large bore 4th axis. There was an awesome huge chuck that sold on Ebay recently, but I decided I needed servo drivers for my big mill more than I needed a chuck right now. |
#26
Posted to rec.crafts.metalworking
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Forward Gears
"Ecnerwal" wrote ... With good programming, lash (at least consistent lash - and with fancy enough programming, I suppose arbitrary lash) is as little an issue as your ability to measure it - just tell the drive to compensate, and have some sort of homing routine so it has a known point to start compensating from. There's also the simple approach, which is to always rotate the same direction - just as you were planning to do by hand. If you need to be CCW 1 degree, go CW 359 degrees (or vice versa) The tooth at the top shows the effect of backlash: https://picasaweb.google.com/KB1DAL/...10370886636434 I made up a script of operations and tried to follow it exactly but problems with the fussy import rotary table interrupted it. I forgot to take up backlash by hand and tighten the clamp. The gear is 3/4" thick and the damage is shallow. jsw |
#27
Posted to rec.crafts.metalworking
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Forward Gears
Sounds like a case of ingenuity overcoming adversity. Go for it. Or you could put a servo or stepper motor on it. Then you got a CNC 4rth axis. I set mine up that way. Karl When I mounted the chuck on the table it was my intention to convert it to CNC eventually. Both of my little machine controllers have an unused 4th port. Its would just be a matter of making a mount and adding a motor. The problem I see is that the drive screw for this rotary table has too much back lash in it. I have not looked yet to see if there is anything I can do about it, but I was thinking it might be easier to just make a spindle for a 4th axis. I was thinking I would like something with a much bigger bore than the average lathe spindle or rotary table. If I keep it under 3000 RPM there are some pretty big bore bearings out there. You might look at my route. I have a servo mounted on an AL plate. Most of the time its bolted to my knee and I run the 4 axis configuration where height tool offsets are done automatically. Then I unbolt the servo and bolt it to the table. Put my dividing head (with considerable backlash) on beside it with a pulley between. Then I load "CNC with 4rth axis" into the control. I do have to crank the knee table by hand. I do have a nice 5C collet fixture with nice heavy duty bearings. if the need arises, I'll mount a huge toothed belt pulley to it and write, "CNC control with lathe". You get the idea. Karl |
#28
Posted to rec.crafts.metalworking
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Forward Gears
I either have the time or the money, but never both at once. Actually I was looking at some of the lathe turned gear cutters. Sounds like the story of my life. Only sometimes I have neither. http://www.youtube.com/watch?v=8UBxNPbg0ls He talks a lot, but it's a good example of what I was thinking of. Maybe an oil hardening drill rod to make the cutter. I don't know, but this little adventure got me reading all kinds of new stuff. Now you're getting more advanced. Hobbing involves coordinated motion of two axis at the same time. You'd need a good CNC 4rth axis. The advantage is one cutter does all gears from tiny to rack. I'd start with the involuter cutter idea. You want to read Ivan Law's book, "gears and gear cutting". there's a section in there on making involute cutters starting with round HSS blanks to make a fly type cutter. I love my devleig boring bars with removable brazed carbide inserts. I can calculate the exact involute shape and plot it at 50X. Lay a paper cutout on the optical comparator with the 50X scope. Start grinding on the baldor carbide grinder and setting the work in the comparator. Only takes a few minutes to get the involute shape perfect. Karl |
#29
Posted to rec.crafts.metalworking
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Forward Gears
"Karl Townsend" wrote in message
... I either have the time or the money, but never both at once. Actually I was looking at some of the lathe turned gear cutters. Sounds like the story of my life. Only sometimes I have neither. http://www.youtube.com/watch?v=8UBxNPbg0ls He talks a lot, but it's a good example of what I was thinking of. Maybe an oil hardening drill rod to make the cutter. I don't know, but this little adventure got me reading all kinds of new stuff. Now you're getting more advanced. Hobbing involves coordinated motion of two axis at the same time. You'd need a good CNC 4rth axis. The advantage is one cutter does all gears from tiny to rack. I'd start with the involuter cutter idea. I don't see why it needs coordinated 4th axis motion. Don't see why the table couldn't be advanced manual by my calculation chart method just like using an involute cutter. You want to read Ivan Law's book, "gears and gear cutting". there's a section in there on making involute cutters starting with round HSS blanks to make a fly type cutter. I just ordered a copy from Amazon. Interestingly a new copy was cheaper than a used copy. Still a single point "fly" cutter type setup is going to be so sloooooow. I love my devleig boring bars with removable brazed carbide inserts. I can calculate the exact involute shape and plot it at 50X. Lay a paper cutout on the optical comparator with the 50X scope. Start grinding on the baldor carbide grinder and setting the work in the comparator. Only takes a few minutes to get the involute shape perfect. Karl |
#30
Posted to rec.crafts.metalworking
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Forward Gears
On Tue, 6 Mar 2012 11:25:38 -0700, "Bob La Londe"
wrote: "Karl Townsend" wrote in message .. . I either have the time or the money, but never both at once. Actually I was looking at some of the lathe turned gear cutters. Sounds like the story of my life. Only sometimes I have neither. http://www.youtube.com/watch?v=8UBxNPbg0ls He talks a lot, but it's a good example of what I was thinking of. Maybe an oil hardening drill rod to make the cutter. I don't know, but this little adventure got me reading all kinds of new stuff. Now you're getting more advanced. Hobbing involves coordinated motion of two axis at the same time. You'd need a good CNC 4rth axis. The advantage is one cutter does all gears from tiny to rack. I'd start with the involuter cutter idea. I don't see why it needs coordinated 4th axis motion. Don't see why the table couldn't be advanced manual by my calculation chart method just like using an involute cutter. Watch that video, the hob cutters are trapezoid shape. If using your method with this cutter you get something that will look like a timing pulley. if you rotate the blank in unison with the hob set up at an angle you will get an involute gear shape. the advantage of the hob is one cutter makes any number of teeth for that gear type. You want to read Ivan Law's book, "gears and gear cutting". there's a section in there on making involute cutters starting with round HSS blanks to make a fly type cutter. I just ordered a copy from Amazon. Interestingly a new copy was cheaper than a used copy. Still a single point "fly" cutter type setup is going to be so sloooooow. True, thank goodness for CNC. Just let it run and do something else. back to that old time or money thing. Karl |
#31
Posted to rec.crafts.metalworking
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Forward Gears
Watch that video, the hob cutters are trapezoid shape. If using your method with this cutter you get something that will look like a timing pulley. if you rotate the blank in unison with the hob set up at an angle you will get an involute gear shape. the advantage of the hob is one cutter makes any number of teeth for that gear type. Actualy that's not right. Run a hob against a part that doesn't move and it will end mill it. The hob cutters are on a helix. Here's the article that i used to draw a gear at 50X: http://www.cartertools.com/involute.html He talks a bit about a homemade hob at the end. |
#32
Posted to rec.crafts.metalworking
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Forward Gears
"Karl Townsend" wrote in message
... Watch that video, the hob cutters are trapezoid shape. If using your method with this cutter you get something that will look like a timing pulley. if you rotate the blank in unison with the hob set up at an angle you will get an involute gear shape. the advantage of the hob is one cutter makes any number of teeth for that gear type. Actualy that's not right. Run a hob against a part that doesn't move and it will end mill it. The hob cutters are on a helix. Here's the article that i used to draw a gear at 50X: http://www.cartertools.com/involute.html He talks a bit about a homemade hob at the end. Just discovered there is an automatic calculator built into CamBam that does involute gears and timing pulleys. Actually I knew there was a gear calculator of some kind in the toolkit, but I never looked at it before. Obviously to use it you need to program backlash compensation in your mill and/or adjust down your backlash adjustments as close as you can. Still, with this you can cut them out of plate with a simple 3 axis CNC mill. Cool beans. Simple profile operation. It even tells you the maximum size end mill you can use. |
#33
Posted to rec.crafts.metalworking
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Forward Gears
Thanks again Stanley. I got those two little gears in earlier this week and
installed them yesterday... ok the day before yesterday now. "Stanley Schaefer" wrote in message ... On Mar 2, 8:13 pm, "Bob La Londe" wrote: The HF mini lathe hasn't been used since I got the slightly bigger much older, and much better HF lathe. I wanted to use it the other day though because it has gear selectable forward and reverse carriage feed. The I remembered I stripped those little nylon gears. I am sure I can get a hold of HF customer service and get a part number for those gears if its not in my manual for the machine, but I was wondering if somebody knew of a source for metal replacements? I know Little Machine Shop was the threading gear set in metal, but I didn't see the rest of the gears for the machine. My next thought was maybe to try and make some metal gears, but I have never done that before. Any suggestions on the approach for that? Best alloy for reasonable wear? LMS had ALL the gears plus extra pitches last I looked. And like the man said, you need a weak link in the chain, otherwise things could get more expensive than just a stripped gear. They are standard metric module gears, guys were using ones scavanged from laser printers and the like for oddball threads. You must not have looked very hard: http://www.littlemachineshop.com/pro...523&category=1 They also have a spare parts kit with some of the other gears, a belt and some fuses. Stan |
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