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DoAll DH-612 Manual Surface Grinder Restoration


Apr 24, 2022
South Dakota, USA
I recently dove into a new project... acquired a 1965 DoAll DH-612 Manual Surface Grinder. Plan is to completely disassemble and restore to factory or better performance.

First of probably a few questions:
I am planning to re-chrome the hand wheels. During disassembly I see the vertical hand wheel does not have a shoulder bolt that inserts through the handle like the other two wheels. It also does not have a gap between the handle and the wheel with some flats to unscrew the wheel from the handle. I am wondering if the handle was pressed into the wheel and not threaded. Can anyone confirm what type of connection this is and have thoughts on how to dis-assemble?

DoAll DH-612 Surface Grinder.jpgHandwheel Vertical 01.jpgHandwheel Vertical 03.jpgHandwheel Vertical 02.jpg
Thanks for sharing. I do have a pdf and the original hard copy manual for the 6-12. I am not seeing details on the connection diagram that could distinguish press-fit from threads (just part numbers). After seeing you could get press-fit handles on McMaster Carr, I concluded this has to be a press fit revolving handle. I pressed it out and all is good.
Column hand wheel.JPG
Spindle Housing Removal Problem

I am trying to remove the spindle assembly from the column. There are two wedges that removed easy enough. There was also a 3/8 bolt on the topside that I removed. I sprayed Aerokroil penetrating oil repeatedly, rigged up some 3/4 threaded rod and steel to press the spindle assembly out and heated the bore that the cartridge slides into. I am not able to budge the spindle assembly at all. I cannot find anything that I am explicitly overlooking in the manual, but there is an inconsistency with the manual and the 3/8 bolt on the topside. The manual calls for a 3" long bolt, but the one I pulled out is only about 1/2" long. I am speculating that the original factory bolt is used to locate the spindle cartridge and at some point broke and a previous owner just stuck a short bolt in the hole. Anyone know if this is a correct assumption or have other thoughts on how to proceed? Thinking I may have to drill the bottom of that 3/8 bolt hole through the cartridge housing to free the spindle assembly.

spindle removal 2.jpgspindle removal 1.jpg
The manual calls for a 3" long bolt, but the one I pulled out is only about 1/2" long.

Actually, I believe this reference in the manual is for the bolt that pulls the wedges together. I don't find a reference to the topside bolt in the manual. Using a pick, the bottom of the hole feels arced in the opposite direction of the spindle cartridge and the depth of the hole sees to be to the outside of the spindle cartridge housing. Thinking I need to drill that 3/8 topside hole a bit to free the spindle assembly. Any other suggestions are welcomed.
Perhaps start a specific thread, ? How to remove the spindle from a DoAll 6-12 surface grinder?

#18 in the 6-18 manual looks like a simple one 5/16-18, one screw casting clamp.

I saw a colonial broach grinder broken and later scrapped because a couple of millwrights could not wait 15 minutes for the service manual. it had locking pins that were ID threaded so one could insert a screw and pull them out. Outside of those pull pins there was a (piggy-back) set screw that held the pull pins in place. *Actually, I now forget how it can apart. but it was clear and simple in the manual.

They just pulled the first set screws and then began whacking it with a piece of wood and a sledgehammer..so broke the wheel head casting. They ordered a new casting and by the time it came, the special motor was lost.

*Is there a reason to remove the spindle?
You might carefully drill the broken bolt out with a 1/4" drill and try an easy out. I don't think I would use a carbide drill as it might get stuck in the hole and be a bigger bugger to get out.

Might bush the hole so the drill goes to the center of the broken.
Might turn the drill slow so as to not burn it up..and see if it makes chips.

My repair guy would often use a left-hand drill bit so as not to push a broken deeper.
I would be very careful with an easy-out to avoid breaking off something hard in the broken screw.

I'm sure there is a PM guy who took one apart and will likely give the proper answers
Spindle Removal Update

Update... I found an old photo in the manual and concluded that top-side hole was most likely just for mounting a worklamp and not a locating bolt. I fabricated some stronger components for pressing the spindle out and it came loose this time.spindle removal 4.JPGspindle removal 3.jpgWorklamp.JPG
With regard to the ways... I haven't had anything on a surface plate or ground any parts, but traversing the table across an indicator with the long ways looks promising(surprise to me). Not making any definite conclusions until I get a closer inspection and grind some parts. The cross-ways are indicating 0.005 over 6 inches, but it appears to be a linear slope. I imagine if I were to grind the table this would get a lot better. I won't be doing that until I have disassembled, cleaned and checked everything for flatness and alignment. I have not scraped before but if needed, I hope to take the class and do it myself. Otherwise I will have to find someone.
If you lay a 6" long parallel on the chuck, straight out from the wheel, and shim up the low end so both ends are zero / zero. Then travel the cross with an indicator set on the parallel this test will tell how the crossways travel ways are accurate. The shimmed zero/zero parallel is acting as a ground-in chuck. Yes, the parallel needs to have a very true/flat top side so it is best to plate check it for true flatness with a blue-in to the plate. The test is done with the mag off because the mag may suck down and bend the parallel.

The same shimmed flat parallel can check the long travel For condition of the machine ways. good to check the long travel in two places, an inch in from the chuck front and back edge.
I have the same grinder. I placed a good 1.5"x.75"x12 parallel against the fence. When I ran the table back and forth, the center section was spot on with a tenths indicator. The ends would raise up .0015" on one end and .002" on the other. i.e. not good. I ground the chuck "flat", and ground 5 blocks (1"x1"x1/4") set at the 4 corners and the middle. The were all within .0002" ...

I think you need a known straight edge to measure what is going on.

Good luck

Doing the shimmed parallel test will give a rough idea of long and cross conditions
This will eliminate the chuck errors from the test to check the way condition.
There is no sense in grinding the chuck if the way condition exceeds your grinding needs.
Very often the close to operator area of the chuck has retained the last chuck grinding so that area is best for simple checking. Checking that chuck area for being flat can tell much about grinder condition.
A rescraped old-school iron way grinder is a better grinder than many/most newer machines and so well worth the effort or cost the make it new.
Chuck tops can be very much in error, I have seen them with a .015 low at the bump rail center, it was an old/very old Abrasive 6-18, after I reground the chuck the machine ran in a few tenths. Likely the machine never ran oil dry. It was not my machine and I was only asked to grind the chuck so that was all I did.
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Think about a cylindrical grinder. The wheel is stationary and the work rotates past the same spot on the wheel. This is what is happening with the 5 blocks and why they are so close. How often will you grind long ones piece parts? If you only grind long parts then you will need to get it scraped. If your going to do small parts. Leave it. Who ever owned it before must have only ground short parts and the ends of the table never wore. Do-Alls also are notorious for the top of the base way getting high in the middle because grit gets into the ways and wears more on the ends.
hi, i just picked up a dh-612. i noticed that the stainless steel band is twisted. is there a place to get replacment parts?