# Model Making Surface Grinder



## cfellows (Jan 24, 2009)

Here's a home built model making surface grinder some of you might find interesting. Unfortunately it's in German, but might provide some inspiration.

http://www.wawu.eu/index.php?option=com_content&view=article&id=11&Itemid=18&lang=en

Chuck


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## Kludge (Jan 24, 2009)

Okay, this is cool. I watched the video a few times and thought about using something other than hydraulics to move the carriage (Google Translate is your friend. ) but overall, a really cool tool. 

Sooo ... who here's gonna make one?

Best regards,

Kludge


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## Kludge (Jan 24, 2009)

After a night of holding the demons a bay via imagineering, I came up with the following:

X-axis drive: Windshield wiper motor. Plenty of oomph and already fitted for reciprocating motion. Stroke length can be varied by not a lot of mechanical wizardry.

Y-axis and Z-axis drives: Steppers. Positive control over movement and reversable without a lot of aggrevation. 

Grinder motor: 12 volt DC, 20,000 rpm motors with the necessary heart aren't all that common but are available. OTOH, motors that turn at around 6000-7000 rpm and have decent power are and they can be geared up as needed. If higher voltage is allowed, a Dremel (or clone) rotary tool would work if solidly mounted to the Z-axis carriage.

Motion control: Optical slit detectors. No moving parts (except the slits attached to the carriage et al) and can be protected from life's little irritations fairly easily. Manual override is easy via toggle switches. 

Someone on ePay sells an oversized milling table for the Unimat SL-1000 so the actual carriage can be made from that. 

That's as far as I got ... I was otherwise quite occupied. Sorry.

BEst regards,

Kludge


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## shred (Jan 24, 2009)

Do you really want 12K RPM on the grinding spindle? I know little about surface grinders except that I press my T&C grinder into use as one occasionally, but most of the commonly available 'full size' SG wheels seem to max out around 3750 or so.


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## T70MkIII (Jan 24, 2009)

Okay, newbie question here - what would the advantage be of building and using something this over just using a mill and lots of light passes?


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## Maryak (Jan 24, 2009)

If its any good - then 1 - accuracy normally around 0.0001" from a surface grinder.
               2 - Surface finish far superior than obtainable with a mill.

How often we need that sort of flat surface. ??? ??? ???

If making tools is your thing then what a great addition to your collection.

Best Regards
Bob


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## GailInNM (Jan 24, 2009)

Richard,
I have an improvised surface grinder. Main advantages for me are:
1. You get a smoother surface finish. About 10 times better than you can get with a milling cutter.
2. You can cut hardened steel.

I mostly use mine to make lathe tools and form tools for the mill. Both out of High Speed Steel. It's more accurate than I can grind by hand.
Gail in NM,USA


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## T70MkIII (Jan 24, 2009)

Thanks, Guys - I hadn't thought about the toolmaking aspect.


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## Kludge (Jan 25, 2009)

shred  said:
			
		

> Do you really want 12K RPM on the grinding spindle? I know little about surface grinders except that I press my T&C grinder into use as one occasionally, but most of the commonly available 'full size' SG wheels seem to max out around 3750 or so.



Considering the scale of the machine, I suspect the surface speed is about the same as your full sized grinder. Most rotary tools run much faster than the big boys so this isn't an unusual shaft speed. Just doing some guesstimating on the fly, it looks as though the grinding wheel is around an inch in diameter whch means it can spin up faster withgout coming to pieces. Usually. 

Bob, it may come in handy for some of my toys given the sizes I like to play with but, yeah, you're right. It's a cool tool to add to an invariably inadequate shop. (C'mon, guys. We all know we need just one more toy to play with!) 

BEst regards,

Kludge


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## Kermit (Feb 19, 2009)

Little hard to make out the diagram but it is a holder for a dremel type tool that attached to the cross slide of the lathe

from here: http://www.krfcompany.com/grinder.html
Kermit


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## Kludge (Feb 19, 2009)

Kermit  said:
			
		

> Little hard to make out the diagram but it is a holder for a dremel type tool that attached to the cross slide of the lathe



Hmmm ... I've seen similar ideas but they mount the tool using the front threads which seems awfully unstable to me. This looks a lot moreso gooderer. Thanks!

Best regards,

Kludge


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## Kermit (Feb 19, 2009)

With a proper holding fixture mounting by the front threads might be good.

enclose it in a round fixture with some screws around the outside to mount and center the dremel. Taper the rear of the fixture down to fit a tailstock morse taper.

Put in your miniature grinding wheel or miniature end mill and get down to; in my case, making scrap parts. ;D  Most likely for me it would be dremel bits that would bite the dust first. I can't say I've ever had much success with those things other than with the micro sized thin kerf cut off wheels. I haven't encountered anything they wouldn't hack through - eventually.


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## Kermit (Feb 19, 2009)




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## Peter Neill (Feb 20, 2009)

Surface Grinders are very handy for all sorts of jobs in the home workshop, and not just flat grinding.

I had to reduce the diameter of a hardened shaft in a small Maxon DC motor. No way to get it apart and turn it down, even if I could get it spot-on to the size needed by turning, so the surface grinder was turned into a cylindrical grinder for the exercise.

Picture 1 - Motor held in grinding vice. 
Luckily the motor shaft was double ended, so I turned up a flywheel of sorts to clamp on the shaft and manually spin it around with:







Picture 2 -setting up to just touch on the wheel:






Picture 3 - Hardened shaft nicely ground down to 4.01mm diameter:







Picture 4 - The reason it had to be ground down. 
That's a 0.6 Module 14 tooth gear, with a 4.00mm H8 bore now press fitted on to the end of the shaft.
The adaptor plate made and fitted on the end of the motor was also surface ground.








Peter


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## kvom (Feb 20, 2009)

Yesterday I used a surface grinder at school to refurb the jaws of my old Bridgeport milling vise. I took the jaws off the vise and ground both sides on each flal to remove many years of minor dings and pits. Then I replaced the jaws on the vise, clamped them together, and put the entire vise on the grinder's mag chuck. Then I was able to grind off all of the drill and mill marks from the tops of the jaws (took off about .03). Finally used a honing stone to debur the edges.

I doubt that vise had been off the swivel since it was new 43 years ago. There were even some old wasp nests in the cavities at the bottom. I had to scrape and hone the bottom of the vise body before grinding the jaw tops.


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## Mainer (Feb 20, 2009)

Speaking from experience...

A Dremel tool does NOT work very well as a surface grinder, toolpost grinder, or whatever. The bearings are nowhere good enough. It may on occasion be handy to mount a Dremel tool on a lathe, but don't expect to get a decent surface finish.


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