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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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Is A Used Surface Plate Good?
A used surface plate just showed up on my doorstep...amazing what
follows me home sometimes. :) This surface plate is a Rahn 34" x 36" black granite with two ledges. So, how does one decide if a surface plate is "good"? If it is "bad", how do you decide whether or not it is worth refurbishing? How much does it cost to refurbish a surface plate and how do they do it? And if it is not worth refurbishing, what have you used an old surface plate for? I've already got a gravestone. ;) Thanks for any suggestions, comments or wisecracks. TMT |
#2
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"Too_Many_Tools" wrote in message
oups.com... A used surface plate just showed up on my doorstep...amazing what follows me home sometimes. :) This surface plate is a Rahn 34" x 36" black granite with two ledges. So, how does one decide if a surface plate is "good"? If it is "bad", how do you decide whether or not it is worth refurbishing? How much does it cost to refurbish a surface plate and how do they do it? And if it is not worth refurbishing, what have you used an old surface plate for? I've already got a gravestone. ;) Thanks for any suggestions, comments or wisecracks. TMT If you find that it's unserviceable as a surface plate, it'd make a fantastic table top or cutting board. It's also a fabulous surface for doing leatherwork... |
#3
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"Too_Many_Tools" wrote in message oups.com... A used surface plate just showed up on my doorstep...amazing what follows me home sometimes. :) This surface plate is a Rahn 34" x 36" black granite with two ledges. So, how does one decide if a surface plate is "good"? If it is "bad", how do you decide whether or not it is worth refurbishing? How much does it cost to refurbish a surface plate and how do they do it? And if it is not worth refurbishing, what have you used an old surface plate for? I've already got a gravestone. ;) Thanks for any suggestions, comments or wisecracks. TMT While I don't recall the details, it used to be routine for a roving service to refinish and calibrate surface plates. They worked through local supply houses, with advance notice. I've not seen it done, so I can't comment on the procedure. One thing is for sure------shipping it two directions to have it done, especially with today's high fuel prices, would be a bad deal. Unless yours has been very poorly used/handled, and unless you intend to use it for QC, I wouldn't lose much sleep over it. Put it to use in your shop, providing a wooden cover for it so it doesn't get banged up unnecessarily. They're super nice for laying out with a height gage, or even inspecting your work. Even if it was out a thou, you'd be unlikely to know, or have it affect you negatively. Make sure it's level, so you don't chase things that you lay on the surface. It's not uncommon to use drill blanks or other round objects in the process of inspecting or making setups. A rigid steel bench with leveling bolts in the legs is a good idea. Once you've had one, you'll wonder how you got along without it. Harold |
#4
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Harold and Susan Vordos wrote:
"Too_Many_Tools" wrote in message oups.com... A used surface plate just showed up on my doorstep...amazing what follows me home sometimes. :) This surface plate is a Rahn 34" x 36" black granite with two ledges. So, how does one decide if a surface plate is "good"? If it is "bad", how do you decide whether or not it is worth refurbishing? How much does it cost to refurbish a surface plate and how do they do it? And if it is not worth refurbishing, what have you used an old surface plate for? I've already got a gravestone. ;) Thanks for any suggestions, comments or wisecracks. TMT While I don't recall the details, it used to be routine for a roving service to refinish and calibrate surface plates. They worked through local supply houses, with advance notice. I've not seen it done, so I can't comment on the procedure. One thing is for sure------shipping it two directions to have it done, especially with today's high fuel prices, would be a bad deal. Unless yours has been very poorly used/handled, and unless you intend to use it for QC, I wouldn't lose much sleep over it. Put it to use in your shop, providing a wooden cover for it so it doesn't get banged up unnecessarily. They're super nice for laying out with a height gage, or even inspecting your work. Even if it was out a thou, you'd be unlikely to know, or have it affect you negatively. That's really the answer. It would have to be a very bad surface plate to be worse than most anything else you'd be doing layout on. Make sure it's level, so you don't chase things that you lay on the surface. It's not uncommon to use drill blanks or other round objects in the process of inspecting or making setups. A rigid steel bench with leveling bolts in the legs is a good idea. Once you've had one, you'll wonder how you got along without it. Harold |
#5
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Make sure it's level, so you don't chase things that you lay on the surface. It's not uncommon to use drill blanks or other round objects in the process of inspecting or making setups. A rigid steel bench with leveling bolts in the legs is a good idea. Once you've had one, you'll wonder how you got along without it. Mine's on a rolling cart, with a couple levels below it. With the cover on it does double duty as a tool cart in the shop. With the cover off, I roll it up beside the optical comparator. I've got "Too-Many-Tools" and no spare room, the cart is pushed into the corner when not in use. Karl |
#6
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On Tue, 30 Aug 2005 21:45:07 -0700, "Harold and Susan Vordos"
wrote: Make sure it's level, so you don't chase things that you lay on the surface. It's not uncommon to use drill blanks or other round objects in the process of inspecting or making setups. A rigid steel bench with leveling bolts in the legs is a good idea. Once you've had one, you'll wonder how you got along without it. Harold Use (3) levelng bolts and pads under it. Not 4. Gunner "Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules. Think of it as having your older brother knock the **** out of you for torturing the cat." Gunner |
#7
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"Too_Many_Tools" wrote in
oups.com: A used surface plate just showed up on my doorstep...amazing what follows me home sometimes. :) This surface plate is a Rahn 34" x 36" black granite with two ledges. So, how does one decide if a surface plate is "good"? If it is "bad", how do you decide whether or not it is worth refurbishing? How much does it cost to refurbish a surface plate and how do they do it? And if it is not worth refurbishing, what have you used an old surface plate for? I've already got a gravestone. ;) Thanks for any suggestions, comments or wisecracks. TMT Unless it's broken, it is probably servicable and useful. There are companies that come around and recertify and refinish surface plates, as Harold mentioned. They lap it to get it back flat. When you build your bench for it, make sure the plate is supported only on 3 rubber isolation mounts. This helps absorb the vibration of the floor. A 3 point mount is pretty much standard for a surface plate. -- Anthony You can't 'idiot proof' anything....every time you try, they just make better idiots. Remove sp to reply via email http://www.machines-cnc.net:81/ |
#8
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Mount an indicater on a angle plate or some hevey peice of metal let it
stick out about a foot . Then turn whatever you have the indicator mounted to .Watch the indicator as it sweeps the 1 foot raduis .Do this all over the surface plate the readings should be within a few tenths(.0000 to .0005 |
#9
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You can 'tram' the surface with an indicator and height gage to see if
there are any low spots. A few ten thousandths should be acceptable for anything except high end quality control, for which you should be using electronic equipment anyway. Bugs |
#10
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"Too_Many_Tools" wrote in message oups.com... A used surface plate just showed up on my doorstep...amazing what follows me home sometimes. :) This surface plate is a Rahn 34" x 36" black granite with two ledges. So, how does one decide if a surface plate is "good"? If it is "bad", how do you decide whether or not it is worth refurbishing? How much does it cost to refurbish a surface plate and how do they do it? And if it is not worth refurbishing, what have you used an old surface plate for? I've already got a gravestone. ;) Thanks for any suggestions, comments or wisecracks. TMT I called Starrett a while back and they will resurface and recertify a surface plate to whatever flatness you need for a very reasonable price. Of course, if you have to spend a fortune to ship it to Mt Airy, North Carolina the "reasonableness" drops off quickly. Steve. |
#11
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On 30 Aug 2005 21:26:55 -0700, "Too_Many_Tools"
wrote: A used surface plate just showed up on my doorstep...amazing what follows me home sometimes. :) This surface plate is a Rahn 34" x 36" black granite with two ledges. So, how does one decide if a surface plate is "good"? If it is "bad", how do you decide whether or not it is worth refurbishing? How much does it cost to refurbish a surface plate and how do they do it? And if it is not worth refurbishing, what have you used an old surface plate for? I've already got a gravestone. ;) Thanks for any suggestions, comments or wisecracks. TMT Being granite, I don't know if it *can* go bad. Metal plates get dings which cause raised areas arond the ding. Granite can chip but the top of the plate is still flat. I suppose excessive sliding of objects over the surface might create"'ruts". Randy |
#12
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On 30 Aug 2005 21:26:55 -0700, Too_Many_Tools wrote:
A used surface plate just showed up on my doorstep...amazing what follows me home sometimes. :) I thought it was just me who has that problem. This surface plate is a Rahn 34" x 36" black granite with two ledges. So, how does one decide if a surface plate is "good"? Naah, it's junk. Send it to me and I'll dispose of it for you, without even charging you. If it is "bad", how do you decide whether or not it is worth refurbishing? How much does it cost to refurbish a surface plate and how do they do it? I would _think_ that, being granite, it probably won't have "much" wear. And outright damage (chips, etc) will be obvious. I'd say find the best standard you have for "straight" and try to find any gaps between it and the face of the stone. I'm not a metrologist, though. And if it is not worth refurbishing, what have you used an old surface plate for? I've already got a gravestone. ;) I watched someone cutting a watermelon on a granite surface plate - seems they had inherited the QA department, and the employer (large company whose name sounds an awful lot like "GE") decided that they didn't need to actually inspect the parts, because (insert mumble here). So, this surface plate had turned into a breakroom table. Un Farking Believable. Thanks for any suggestions, comments or wisecracks. What, here? But yeah, get a straightedge and a bright light. If there's any visible gaps, get out the feeler gages and see how bad they are, and compare that with your personal tolerance. |
#13
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Too_Many_Tools writes:
So, how does one decide if a surface plate is "good"? There is a chapter on this in Connelly's _Machine Tool Reconditiong_. Ordinary gages and indicators are not precise enough to calibrate a surface plate, although they could detect gross problems. You're in the realm of ultra-flat reference gages and solvent-evaporation marking. Being granite, it probably is still good as new. Minor surface dings are of no consequence. If you inspect it closely with glaring reflected light, you should see the original polished surface quality, as opposed to dullness from misuse or abuse. |
#14
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On Wed, 31 Aug 2005 16:55:05 -0500, Richard J Kinch wrote:
If you inspect it closely with glaring reflected light, you should see the original polished surface quality, as opposed to dullness from misuse or abuse. That is a really, really good point. Polish, if intact, tells you that the flatness is still intact. Oversimplified, but probably an excellent measure of the "health" of the stone. |
#15
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there are other companies that will come out and calibrate you surface plate
and refinish if needed, our company uses Rockford Calibration, Rockford, IL They use a tool that looks like a long block of steel with an indicator mounted to one end, the indicator rides on some kind of shoe that reads in the millionths I believe. He has a plate that he uses diamond dust on to resurface the plates and they can fill in big gunges with some kind of body filler. we had them in for the last few years to do our plates, when they were in the last time they found 4 of the small plates out of tolerance and it was cheaper to by new ones than redo them, were talking about roughly 2' X 3' plates. Ours are calibrated to .0005 and one of them has a hole thats .0045 in the middle from not being cleaned enough. We have the Starret Altissimo height stands that we use along with the Brown and Sharpe stands. The problem is that all shop grit lands on your plate and whatever you push around on the plate pushes the grit into the voids on the plate. We've had the plates for 10 years and we usually run 24/7 so they get plenty of use by the operators. If you had a good straight edge you could probably measure the gap under the edge to find out how bad it is. "Too_Many_Tools" wrote in message oups.com... A used surface plate just showed up on my doorstep...amazing what follows me home sometimes. :) This surface plate is a Rahn 34" x 36" black granite with two ledges. So, how does one decide if a surface plate is "good"? If it is "bad", how do you decide whether or not it is worth refurbishing? How much does it cost to refurbish a surface plate and how do they do it? And if it is not worth refurbishing, what have you used an old surface plate for? I've already got a gravestone. ;) Thanks for any suggestions, comments or wisecracks. TMT |
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