milling square keyway slot INSIDE diameter.
I am making an attachment to my knee mill height hand crank. I drilled
a hole in a rod to match the diameter of the crank shaft. However there is a keyway that I need to mill out of my adaptor on the INSIDE Diameter. I dont see a Woodruff cutter working in this 5/8" hole. I can mill it but it will not have square corners. What is needed to get the square slot? Thanks Steve |
"gtslabs" wrote in message oups.com... I am making an attachment to my knee mill height hand crank. I drilled a hole in a rod to match the diameter of the crank shaft. However there is a keyway that I need to mill out of my adaptor on the INSIDE Diameter. I dont see a Woodruff cutter working in this 5/8" hole. I can mill it but it will not have square corners. What is needed to get the square slot? Thanks Steve There are two "right" ways to do it. One is with a keyway broach (not real cheap). They come in all the standard sizes. The other way is to cut it with a shaper, if you know someone who has one. But, for a "one shot" deal, you can use the mill as a shaper. Run an end mill down through it to get it to the right width and depth. Then take a boring bar or grind a piece of drill rod to make an appropriate cutter and chuck it in the mill. Put the mill into back gear, if it has one. Rotate the mill to position the cutter (easy if you can get at the belts...) and then use the quill feed to drive the cutter down through the work, cutting out the corners. Use the table feed to move the work for successive cuts. You can do the same thing with the lathe, holding the work in the chuck and driving the boring bar with the carriage feed. Jerry |
Jerry Foster wrote:
"gtslabs" wrote in message oups.com... I am making an attachment to my knee mill height hand crank. I drilled a hole in a rod to match the diameter of the crank shaft. However there is a keyway that I need to mill out of my adaptor on the INSIDE Diameter. I dont see a Woodruff cutter working in this 5/8" hole. I can mill it but it will not have square corners. What is needed to get the square slot? Thanks Steve .................. But, for a "one shot" deal, you can use the mill as a shaper. Run an end mill down through it to get it to the right width and depth. Then take a boring bar or grind a piece of drill rod to make an appropriate cutter and chuck it in the mill. Put the mill into back gear, if it has one. Rotate the mill to position the cutter (easy if you can get at the belts...) and then use the quill feed to drive the cutter down through the work, cutting out the corners. Use the table feed to move the work for successive cuts. You can do the same thing with the lathe, holding the work in the chuck and driving the boring bar with the carriage feed. Jerry I don't think so, Jerry! |
Tom wrote:
Jerry Foster wrote: "gtslabs" wrote in message groups.com... I am making an attachment to my knee mill height hand crank. I drilled a hole in a rod to match the diameter of the crank shaft. However there is a keyway that I need to mill out of my adaptor on the INSIDE Diameter. I dont see a Woodruff cutter working in this 5/8" hole. I can mill it but it will not have square corners. What is needed to get the square slot? Thanks Steve .................. But, for a "one shot" deal, you can use the mill as a shaper. Run an end mill down through it to get it to the right width and depth. Then take a boring bar or grind a piece of drill rod to make an appropriate cutter and chuck it in the mill. Put the mill into back gear, if it has one. Rotate the mill to position the cutter (easy if you can get at the belts...) and then use the quill feed to drive the cutter down through the work, cutting out the corners. Use the table feed to move the work for successive cuts. You can do the same thing with the lathe, holding the work in the chuck and driving the boring bar with the carriage feed. Jerry I don't think so, Jerry! Have you tried it? I have seen it done quite often on the lathe. While it works better in aluminum and brass, you can use the lathe for small or odd sized keyways. A broach or shaper is preferred but one has to be adaptable and use whats on hand. I would not want to do it on a daily basis, as it is time consuming. |
We do one 1/4" blind key way per year using the mill as a shaper. Take
off about .002" per pass using the downfeed handle. Royal pain on the arm, I'm sure it is not much better on the mill. Tom wrote: Jerry Foster wrote: "gtslabs" wrote in message groups.com... I am making an attachment to my knee mill height hand crank. I drilled a hole in a rod to match the diameter of the crank shaft. However there is a keyway that I need to mill out of my adaptor on the INSIDE Diameter. I dont see a Woodruff cutter working in this 5/8" hole. I can mill it but it will not have square corners. What is needed to get the square slot? Thanks Steve .................. But, for a "one shot" deal, you can use the mill as a shaper. Run an end mill down through it to get it to the right width and depth. Then take a boring bar or grind a piece of drill rod to make an appropriate cutter and chuck it in the mill. Put the mill into back gear, if it has one. Rotate the mill to position the cutter (easy if you can get at the belts...) and then use the quill feed to drive the cutter down through the work, cutting out the corners. Use the table feed to move the work for successive cuts. You can do the same thing with the lathe, holding the work in the chuck and driving the boring bar with the carriage feed. Jerry I don't think so, Jerry! |
For a hand crank application, you might find it suitable to make the boached
hole using 2 pieces. The crank shaft could be drilled or bored to the diameter of the exposed key height (shaft dia + key height). If you choose a section of tubing which fits the shaft diameter, that's got the same wall thickness as the exposed height of the key, it can be slotted to the key width. This tubing section would fit the crank shaft like a slotted bushing. Use any number of methods to secure the slotted tube into the hand crank shaft cavity (which would be the diameter of the shaft plus the key height). Weld, plug weld thru holes, pin, set screws etc. WB ................ "gtslabs" wrote in message oups.com... I am making an attachment to my knee mill height hand crank. I drilled a hole in a rod to match the diameter of the crank shaft. However there is a keyway that I need to mill out of my adaptor on the INSIDE Diameter. I dont see a Woodruff cutter working in this 5/8" hole. I can mill it but it will not have square corners. What is needed to get the square slot? Thanks Steve ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
gtslabs wrote: I am making an attachment to my knee mill height hand crank. I drilled a hole in a rod to match the diameter of the crank shaft. However there is a keyway that I need to mill out of my adaptor on the INSIDE Diameter. I dont see a Woodruff cutter working in this 5/8" hole. I can mill it but it will not have square corners. What is needed to get the square slot? Thanks Steve I'm assuming it's a thru hole and key thru. plunge out with endmill or plug and drill. mount in vice, file the corners. sjm1 |
machineman wrote:
Tom wrote: Jerry Foster wrote: "gtslabs" wrote in message groups.com... I am making an attachment to my knee mill height hand crank. I drilled a hole in a rod to match the diameter of the crank shaft. However there is a keyway that I need to mill out of my adaptor on the INSIDE Diameter. I dont see a Woodruff cutter working in this 5/8" hole. I can mill it but it will not have square corners. What is needed to get the square slot? Thanks Steve .................. But, for a "one shot" deal, you can use the mill as a shaper. Run an end mill down through it to get it to the right width and depth. Then take a boring bar or grind a piece of drill rod to make an appropriate cutter and chuck it in the mill. Put the mill into back gear, if it has one. Rotate the mill to position the cutter (easy if you can get at the belts...) and then use the quill feed to drive the cutter down through the work, cutting out the corners. Use the table feed to move the work for successive cuts. You can do the same thing with the lathe, holding the work in the chuck and driving the boring bar with the carriage feed. Jerry I don't think so, Jerry! Have you tried it? I have seen it done quite often on the lathe. While it works better in aluminum and brass, you can use the lathe for small or odd sized keyways. A broach or shaper is preferred but one has to be adaptable and use whats on hand. I would not want to do it on a daily basis, as it is time consuming. "Driving the boring bar with the carriage feed?" Yep when boring a hole. To use the carriage feed requires the chuck rotating.. If you mean using the "carriage hand wheel" to reciprocate the carriage rather than the carriage feed? Then yes, many times. |
In article , Tom says...
"Driving the boring bar with the carriage feed?" Yep when boring a hole. To use the carriage feed requires the chuck rotating.. If you mean using the "carriage hand wheel" to reciprocate the carriage rather than the carriage feed? Then yes, many times. Carrige feed in this context obviously means using the longitutinal feed for the carriage, aka handwheel. Jim -- ================================================== please reply to: JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com ================================================== |
In article .com, gtslabs
says... ... What is needed to get the square slot? Another approach is to not use the keyway on the existing shaft. You could: Cross drill for a taper pin, or Machine the shaft and handle for a 'dutchman' which is a round key. The idea is you assemble the shaft to the hub, and drill the face of the assembly, centered at the parting line between the two. A tight fitting round pin is then driven into the hole. If you've ever taken apart a southbend crossfeed handle, you'll know what this technique looks like. Jim -- ================================================== please reply to: JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com ================================================== |
On Sat, 11 Jun 2005 00:49:10 GMT, "Jerry Foster"
wrote: You can do the same thing with the lathe, holding the work in the chuck and driving the boring bar with the carriage feed. Jerry I've heard about making a gear this way on a Navy ship while at sea. Indexing must have been a pain! Randy |
Randy Replogle wrote: On Sat, 11 Jun 2005 00:49:10 GMT, "Jerry Foster" wrote: You can do the same thing with the lathe, holding the work in the chuck and driving the boring bar with the carriage feed. Jerry I've heard about making a gear this way on a Navy ship while at sea. Indexing must have been a pain! Randy Lots of things can be machined this way, though if the load is heavy it does the handwheel mechanism no good. But what the heck: for a hobbyist, the lathe will likely outlive him anyway, and refusing to occasionally do this sort of stuff to preserve his machine just limits his capabilities or forces him to buy more expensive machinery or farm the job out. I've used the method to clean out the insulation between commutator segments on generators and series-wound motors. Works OK and doesn't hurt anything. Dan |
"jim rozen" wrote in message ... In article .com, gtslabs says... ... What is needed to get the square slot? Another approach is to not use the keyway on the existing shaft. You could: Cross drill for a taper pin, or Machine the shaft and handle for a 'dutchman' which is a round key. The idea is you assemble the shaft to the hub, and drill the face of the assembly, centered at the parting line between the two. A tight fitting round pin is then driven into the hole. If you've ever taken apart a southbend crossfeed handle, you'll know what this technique looks like. Jim I have drilled and tapped the hole and used a set screw. Richard W. |
jim rozen wrote:
In article , Tom says... "Driving the boring bar with the carriage feed?" Yep when boring a hole. To use the carriage feed requires the chuck rotating.. If you mean using the "carriage hand wheel" to reciprocate the carriage rather than the carriage feed? Then yes, many times. Carrige feed in this context obviously means using the longitutinal feed for the carriage, aka handwheel. Jim Obviously? Write MS software manuals do you, Jim? Tom |
"Tom" wrote in message ... Jerry Foster wrote: "gtslabs" wrote in message oups.com... I am making an attachment to my knee mill height hand crank. I drilled a hole in a rod to match the diameter of the crank shaft. However there is a keyway that I need to mill out of my adaptor on the INSIDE Diameter. I dont see a Woodruff cutter working in this 5/8" hole. I can mill it but it will not have square corners. What is needed to get the square slot? Thanks Steve .................. But, for a "one shot" deal, you can use the mill as a shaper. Run an end mill down through it to get it to the right width and depth. Then take a boring bar or grind a piece of drill rod to make an appropriate cutter and chuck it in the mill. Put the mill into back gear, if it has one. Rotate the mill to position the cutter (easy if you can get at the belts...) and then use the quill feed to drive the cutter down through the work, cutting out the corners. Use the table feed to move the work for successive cuts. You can do the same thing with the lathe, holding the work in the chuck and driving the boring bar with the carriage feed. Jerry I don't think so, Jerry! I think so Tom! I've done it quite a few times. If you don't have a key broaching machine our Minuteman broaches, this is about the only alternative. Its slow and hard work, but if you have half a plant,and fifty employees waiting for a pump that requires keyway, then you just do it. Tom Miller |
"Tom" wrote in message ... machineman wrote: Tom wrote: Jerry Foster wrote: "gtslabs" wrote in message groups.com... I am making an attachment to my knee mill height hand crank. I drilled a hole in a rod to match the diameter of the crank shaft. However there is a keyway that I need to mill out of my adaptor on the INSIDE Diameter. I dont see a Woodruff cutter working in this 5/8" hole. I can mill it but it will not have square corners. What is needed to get the square slot? Thanks Steve .................. But, for a "one shot" deal, you can use the mill as a shaper. Run an end mill down through it to get it to the right width and depth. Then take a boring bar or grind a piece of drill rod to make an appropriate cutter and chuck it in the mill. Put the mill into back gear, if it has one. Rotate the mill to position the cutter (easy if you can get at the belts...) and then use the quill feed to drive the cutter down through the work, cutting out the corners. Use the table feed to move the work for successive cuts. You can do the same thing with the lathe, holding the work in the chuck and driving the boring bar with the carriage feed. Jerry I don't think so, Jerry! Have you tried it? I have seen it done quite often on the lathe. While it works better in aluminum and brass, you can use the lathe for small or odd sized keyways. A broach or shaper is preferred but one has to be adaptable and use whats on hand. I would not want to do it on a daily basis, as it is time consuming. "Driving the boring bar with the carriage feed?" Yep when boring a hole. To use the carriage feed requires the chuck rotating.. If you mean using the "carriage hand wheel" to reciprocate the carriage rather than the carriage feed? Then yes, many times. Who gives a **** what you call it. Just get on with the job! |
"jim rozen" wrote in message ... In article .com, gtslabs says... ... What is needed to get the square slot? Another approach is to not use the keyway on the existing shaft. You could: Cross drill for a taper pin, or Machine the shaft and handle for a 'dutchman' which is a round key. The idea is you assemble the shaft to the hub, and drill the face of the assembly, centered at the parting line between the two. A tight fitting round pin is then driven into the hole. Here in Auz,they usually call that a "Scotch key".They tap the hole and put a grub screw into it so that it can be removed if necessary |
"Randy Replogle" wrote in message ... On Sat, 11 Jun 2005 00:49:10 GMT, "Jerry Foster" wrote: You can do the same thing with the lathe, holding the work in the chuck and driving the boring bar with the carriage feed. Jerry I've heard about making a gear this way on a Navy ship while at sea. Indexing must have been a pain! Randy Indexing is usually done in this trick by putting a wedge between the teeth of the gear on the lathe spindle. If you want some multiple of teeth that isn't divisible by the number of teeth on the gear, then tough luck! |
Tom Miller wrote:
"Tom" wrote in message ... Jerry Foster wrote: "gtslabs" wrote in message oups.com... I am making an attachment to my knee mill height hand crank. I drilled a hole in a rod to match the diameter of the crank shaft. However there is a keyway that I need to mill out of my adaptor on the INSIDE Diameter. I dont see a Woodruff cutter working in this 5/8" hole. I can mill it but it will not have square corners. What is needed to get the square slot? Thanks Steve .................. But, for a "one shot" deal, you can use the mill as a shaper. Run an end mill down through it to get it to the right width and depth. Then take a boring bar or grind a piece of drill rod to make an appropriate cutter and chuck it in the mill. Put the mill into back gear, if it has one. Rotate the mill to position the cutter (easy if you can get at the belts...) and then use the quill feed to drive the cutter down through the work, cutting out the corners. Use the table feed to move the work for successive cuts. You can do the same thing with the lathe, holding the work in the chuck and driving the boring bar with the carriage feed. Jerry I don't think so, Jerry! I think so Tom! I've done it quite a few times. If you don't have a key broaching machine our Minuteman broaches, this is about the only alternative. Its slow and hard work, but if you have half a plant,and fifty employees waiting for a pump that requires keyway, then you just do it. Tom Miller Quite the oz hero, Tom, pity about your English comprehension. |
Tom Miller wrote:
"Tom" wrote in message ... machineman wrote: Tom wrote: Jerry Foster wrote: "gtslabs" wrote in message groups.com... I am making an attachment to my knee mill height hand crank. I drilled a hole in a rod to match the diameter of the crank shaft. However there is a keyway that I need to mill out of my adaptor on the INSIDE Diameter. I dont see a Woodruff cutter working in this 5/8" hole. I can mill it but it will not have square corners. What is needed to get the square slot? Thanks Steve .................. But, for a "one shot" deal, you can use the mill as a shaper. Run an end mill down through it to get it to the right width and depth. Then take a boring bar or grind a piece of drill rod to make an appropriate cutter and chuck it in the mill. Put the mill into back gear, if it has one. Rotate the mill to position the cutter (easy if you can get at the belts...) and then use the quill feed to drive the cutter down through the work, cutting out the corners. Use the table feed to move the work for successive cuts. You can do the same thing with the lathe, holding the work in the chuck and driving the boring bar with the carriage feed. Jerry I don't think so, Jerry! Have you tried it? I have seen it done quite often on the lathe. While it works better in aluminum and brass, you can use the lathe for small or odd sized keyways. A broach or shaper is preferred but one has to be adaptable and use whats on hand. I would not want to do it on a daily basis, as it is time consuming. "Driving the boring bar with the carriage feed?" Yep when boring a hole. To use the carriage feed requires the chuck rotating.. If you mean using the "carriage hand wheel" to reciprocate the carriage rather than the carriage feed? Then yes, many times. Who gives a **** what you call it. Just get on with the job! Perhaps the person who asked the original question? Not everyone shares your slapdash approach to accuracy. |
machineman wrote:
Tom wrote: Jerry Foster wrote: "gtslabs" wrote in message groups.com... I am making an attachment to my knee mill height hand crank. I drilled a hole in a rod to match the diameter of the crank shaft. However there is a keyway that I need to mill out of my adaptor on the INSIDE Diameter. I dont see a Woodruff cutter working in this 5/8" hole. I can mill it but it will not have square corners. What is needed to get the square slot? Thanks Steve .................. But, for a "one shot" deal, you can use the mill as a shaper. Run an end mill down through it to get it to the right width and depth. Then take a boring bar or grind a piece of drill rod to make an appropriate cutter and chuck it in the mill. Put the mill into back gear, if it has one. Rotate the mill to position the cutter (easy if you can get at the belts...) and then use the quill feed to drive the cutter down through the work, cutting out the corners. Use the table feed to move the work for successive cuts. You can do the same thing with the lathe, holding the work in the chuck and driving the boring bar with the carriage feed. Jerry I don't think so, Jerry! Have you tried it? I have seen it done quite often on the lathe. While it works better in aluminum and brass, you can use the lathe for small or odd sized keyways. A broach or shaper is preferred but one has to be adaptable and use whats on hand. I would not want to do it on a daily basis, as it is time consuming. "Driving the boring bar with the carriage feed?" Yep when boring a hole. To use the carriage feed requires the chuck rotating.. If you mean using the "carriage hand wheel" to reciprocate the carriage rather than the carriage feed? Then yes, many times. Let's see....ummmm.... ya got a compound feed (with a handwheel/crank), and ya got a crossslide feed (with a handwheel/crank or under power), and ya got yer basic carriage feed (with a handwheel/crank or under power). So, Tom, are you telling me that you *can't* move the carriage on your lathe *without* the chuck spinning??? Maybe you ought to disengage the half-nuts and try something new.... Ken. |
gtslabs wrote: I am making an attachment to my knee mill height hand crank. I drilled a hole in a rod to match the diameter of the crank shaft. However there is a keyway that I need to mill out of my adaptor on the INSIDE Diameter. I dont see a Woodruff cutter working in this 5/8" hole. I can mill it but it will not have square corners. What is needed to get the square slot? Thanks Steve Another option would be to make your own broach and bushing. HSM had an article on that quite a few years ago, and I made one to do a keyway job. It worked well. The bushing is simply a piece turned to fit the bore, with a shoulder to keep it from dropping through and a milled slot to take the broach. The broach is a single-tooth one, easily made with a mill and file. I didn't have any tool steel of the right size handy, so made mine from low carbon steel and case hardened it. Works fine. The main difference between this and a commercial broach and bushing is that the commercial broach has many teeth set progresively deeper, and can often make the keyway in one pass. With the single-point broach, you need a bunch of shims. Make a pass, add or change shims, make another pass.... With the single-point cutter, you don't want any side clearance, so that the cutter will make and follow a straight slot. Top clearance only. John Martin |
gtslabs wrote: I am making an attachment to my knee mill height hand crank. I drilled a hole in a rod to match the diameter of the crank shaft. However there is a keyway that I need to mill out of my adaptor on the INSIDE Diameter. I dont see a Woodruff cutter working in this 5/8" hole. I can mill it but it will not have square corners. What is needed to get the square slot? Thanks Steve Another option would be to make your own broach and bushing. HSM had an article on that quite a few years ago, and I made one to do a keyway job. It worked well. The bushing is simply a piece turned to fit the bore, with a shoulder to keep it from dropping through and a milled slot to take the broach. The broach is a single-tooth one, easily made with a mill and file. I didn't have any tool steel of the right size handy, so made mine from low carbon steel and case hardened it. Works fine. The main difference between this and a commercial broach and bushing is that the commercial broach has many teeth set progresively deeper, and can often make the keyway in one pass. With the single-point broach, you need a bunch of shims. Make a pass, add or change shims, make another pass.... With the single-point cutter, you don't want any side clearance, so that the cutter will make and follow a straight slot. Top clearance only. John Martin Interesting, John. Did you use an arbor press, vise, or what to press the cutter through? Were there any specs (that you remember of) concerning the "height" of the cutter/and the bar stock the cutter is milled into? (or the depth of the slot into the bushing?) Thanks. Ken. |
In article , Tom says...
Carrige feed in this context obviously means using the longitudinal feed for the carriage, aka handwheel. Obviously? Write MS software manuals do you, Jim? What's software. Jim -- ================================================== please reply to: JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com ================================================== |
jim rozen wrote:
In article , Tom says... Carrige feed in this context obviously means using the longitudinal feed for the carriage, aka handwheel. Obviously? Write MS software manuals do you, Jim? What's software. Jim In a metalworking context? Digital stuff that protects chucks from hardware such as bone. |
Ken Sterling wrote: Interesting, John. Did you use an arbor press, vise, or what to press the cutter through? Were there any specs (that you remember of) concerning the "height" of the cutter/and the bar stock the cutter is milled into? (or the depth of the slot into the bushing?) Thanks. Ken. I believe that I used an arbor press. That isn't critical, though, as the force needed to drive the single point cutter isn't very great. The pulley that I keyed was aluminum, but I don't think steel would have been that much more of a problem. My arbor press is an old Greenerd #1 which is rated at 1/4 ton. While I suspect I often overload it, it didn't require a huge amount of pressure to cut the keyway. A multi-toothed broach would have required much more pressure. Made and used this cutter maybe 15 years ago, so I can't remember the specs. But I still have it, so I measured. Pulley bore .875", bushing turned to a close sliding fit. Keyway and cutter tooth width .1875". The cutter is actually a piece of .500" square stock, milled to that .1875" width, centered, for the top .25" or so. Profile is like that of a nut for a T slot. There is no good reason to make the cutter that T profile rather than simply to the width of the keyway. All I had for a mill at that time was a milling column on a Sherline, which was not the greatest at heavy cuts in steel. And it gave me a better finish on the bottom of the slot than the sides. So I opted to use a wider bottom rather than the sides of the slot to keep the cutter from rocking. The single tooth is no wider than the body of the cutter is at the top, so there is no side clearange or side rake. The cutting edge is proud of the top surface of the cutter by .014", both in front of and behind the tooth. The top surface of the tooth has 2 degree clearance. The front of the tooth is at 72 degrees - 18 degrees of rake. The front and top of the tooth were lightly stoned after hardening. The overall length of the cutter is about 4", but only the first 2" have the leg of the T sticking up. The tooth is about centered in the 2" T section, with the long tail behind it allowing it to be pressed completely through the workpiece. With my cutter having such a wide base, the slot is obviously milled deep into the bushing. Deeper than it has to be, as I used a lot of shims. If you use a cutter the width of the keyway, a deep slot will better prevent any twisting of the cutter. As above, mine relied more in the wide bottom for that. Hope this helps, John Martin |
It's called a broach.
|
Ken Sterling wrote: Interesting, John. Did you use an arbor press, vise, or what to press the cutter through? Were there any specs (that you remember of) concerning the "height" of the cutter/and the bar stock the cutter is milled into? (or the depth of the slot into the bushing?) Thanks. Ken. I believe that I used an arbor press. That isn't critical, though, as the force needed to drive the single point cutter isn't very great. The pulley that I keyed was aluminum, but I don't think steel would have been that much more of a problem. My arbor press is an old Greenerd #1 which is rated at 1/4 ton. While I suspect I often overload it, it didn't require a huge amount of pressure to cut the keyway. A multi-toothed broach would have required much more pressure. Made and used this cutter maybe 15 years ago, so I can't remember the specs. But I still have it, so I measured. Pulley bore .875", bushing turned to a close sliding fit. Keyway and cutter tooth width .1875". The cutter is actually a piece of .500" square stock, milled to that .1875" width, centered, for the top .25" or so. Profile is like that of a nut for a T slot. There is no good reason to make the cutter that T profile rather than simply to the width of the keyway. All I had for a mill at that time was a milling column on a Sherline, which was not the greatest at heavy cuts in steel. And it gave me a better finish on the bottom of the slot than the sides. So I opted to use a wider bottom rather than the sides of the slot to keep the cutter from rocking. The single tooth is no wider than the body of the cutter is at the top, so there is no side clearange or side rake. The cutting edge is proud of the top surface of the cutter by .014", both in front of and behind the tooth. The top surface of the tooth has 2 degree clearance. The front of the tooth is at 72 degrees - 18 degrees of rake. The front and top of the tooth were lightly stoned after hardening. The overall length of the cutter is about 4", but only the first 2" have the leg of the T sticking up. The tooth is about centered in the 2" T section, with the long tail behind it allowing it to be pressed completely through the workpiece. With my cutter having such a wide base, the slot is obviously milled deep into the bushing. Deeper than it has to be, as I used a lot of shims. If you use a cutter the width of the keyway, a deep slot will better prevent any twisting of the cutter. As above, mine relied more in the wide bottom for that. Hope this helps, John Martin Thanks! Good info. Question tho... If I'm picturing this correctly, you would mill a slot in the bushing the full depth of the cutter bar (broach) and then start slipping shims under it for each pass? This is assuming using a rectangular cutter bar instead of the "T" shape. The "bushing" then could be solid with no hole through the center??? Thanks. Ken. |
Ken Sterling wrote: Thanks! Good info. Question tho... If I'm picturing this correctly, you would mill a slot in the bushing the full depth of the cutter bar (broach) and then start slipping shims under it for each pass? This is assuming using a rectangular cutter bar instead of the "T" shape. The "bushing" then could be solid with no hole through the center??? Thanks. Ken. You are picturing it correctly. The bushing is indeed solid. The slot, on mine, goes deeper than the center of the bushing. If you look at the keyway broach sets sold by MSC and others, you'll see good illustrations of the bushings and broaches. The only difference with a single-tooth broach is that, since you can't expect that one tooth to cut to full depth in one pass, you use shims and take many passes, adding to the shim thickness with eack pass. John Martin |
Ken Sterling wrote: Thanks! Good info. Question tho... If I'm picturing this correctly, you would mill a slot in the bushing the full depth of the cutter bar (broach) and then start slipping shims under it for each pass? This is assuming using a rectangular cutter bar instead of the "T" shape. The "bushing" then could be solid with no hole through the center??? Thanks. Ken. You are picturing it correctly. The bushing is indeed solid. The slot, on mine, goes deeper than the center of the bushing. If you look at the keyway broach sets sold by MSC and others, you'll see good illustrations of the bushings and broaches. The only difference with a single-tooth broach is that, since you can't expect that one tooth to cut to full depth in one pass, you use shims and take many passes, adding to the shim thickness with eack pass. John Martin Gotcha. Thanks again, John Ken. |
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