Ingar-RT618 Surface Grinder (Boyar Schultz clone)

[john mills]

did the chuck measure the same thickness at each side (was it parallel)
i would make sure the table on the machine is very clean  and flat  then might shim the mag table base up
and just clean up the base   make sure it is flat  carefull shimming so the mag table does not sag between shims
then clean and mount the table in its proper position no packing or shims it should be flat on the machine table were it is going to stay  then grind the top whatever it needs to clean up   then  you should have a flat table
for future grinding   .make sure to dress the wheel for final finishing .
I spent a lot of time on milling machines machining tool steel 500mm lengths to get them flat without distortion
with in fine tolerances i used a mag table on the milling machine it was necessary to shim to support so no flexing
then machining  then turning over and re machining several times each time getting flatter to be happy they would be straight.          the steel will flex if you put and pressure on it it does not have to be thin.
the mag table will flex if it is not supported .         
       John

[john mills]

Hi
it was over 30 years ago when i worked on a grinder the same
i am just remembering    i was at work an given the job to see what i could do.see if i could re machine the slides.
one of the fitters had dismantled it.and the slides were well worn .i only had milling machines to use.i don't remember which one i used possibly a well used mazac  V10 a vertical spindle cnc machine.
all could do was machine it the best i could .from memory i was pleased with the way it turn out  .the ways were
well worn.   i suspect your errors could be wear too.if you only clean up the base of the mag table you will retain the form of the table if you need to fit it to another machine regrinding will return the mag table to its original basic shape.
I had nearly forgotten about that job i only rebuilt the machine i did not take it apart.

 John

[Joco]

Thanks John. Appreciate the insights from someone who has “been there, done that”.

The ultimate game plan will be to recondition this machine. That will be a project in itself. But I will teach myself some basic scraping skills first. I have iron on order to make some reference straight edges from.

The carriage to base ways are metal on metal and all flat. So in theory relatively simple to recondition. Just need to keep in a common plan and keep square to the column.

The table ways on the carriage are teflon/relon/turcite lined. Plus one is V and one is flat. Stripping and relaying the bearing compound wont be too hard. Getting it scraped in will be trickier due to the different shapes and the length. At circa 700mm I will need to source/make a reference of at least 600mm. OR use the ways under the table as the reference. They have zero wear as its all gone into the teflon.

Once that is all done and tested to spec I would grind the table top in. Until then I am inclined to avoid doing anything “destructive” to table and mag chuck.

I did some test grinding last night on my undusted but shimmed chuck. I deliberately put the test piece in an area of the chuck I had measured as being flat. I mic’d the results.  I was within 0.001 to 0.002mm around the piece. So between half a tenth and a tenth if you are into imperial.  Its a mild steel test piece so not the easiest to get a good finish. But to the touch its super smooth and no waves catching the light. So all up not too bad given Im still learning the feel of grinding and settling this machine in.

[Joco]

A little update on progress.

Had some fun with the little CNC and whipped up some new "cooler" clamps (pic #1) for the mag chuck. What was there were some utalitarian rectangular flat bar strap clamps.

I didnt have a wheel dressing tool so had a ferret through the scrap bin and came up with some steel to create pic #2.  vertical is at the recommended 15deg and I have a side mounting hole as well for side dressing the wheel.

Cheers,
J.

[Joco]

A successful day getting the coolant system wired and plumbed up.  Ran the pump for a bit to get the old pipes well flushed. Pic attached of the coolant tank in its position beside the grinder.   I have a filter sock on order for the return flow.  Once that arrives I will be making a holder for it out of some downflow drainage pipe and fittings which will be part of the return system.  I have seen Solid Rock Machining (youtube channel that do a lot of grinding work) use this method to filter the return fluid.  The filter socks are pretty cheap and should last quite some time before having to be replaced. The upshot in theory should mean the coolant is cleaner longer and should last longer before need replacement.

Cheers,
J.

[Joco]

Got the coolant fired up today and found a bit of an issue with leaks from under the back spash guard.  I started to look at different sealant options until a good friend suggested using the rubber from a bike inner tube.  Such a clever idea.

Video of the working solution. No leaks.   
<a href="https://www.youtube.com/watch?v=7lfot8uM2PU" target="_blank">http://www.youtube.com/watch?v=7lfot8uM2PU</a>

So going down the pics in order ...

[1] Coolant running with the splash guard visible in the back ground.

[2] Rear view of the splash guard.

[3] Shows the groove that the splash guard goes in and you can see the coolant that has leaked out from under it and is sitting on the way protection.

[4] The rubber protruding from under the splash guard is the inner tube rubber that is being used to create a water tight seal.  Which from the video works a treat.  Without the seal there is coolant dribbling down from under the guard in little streams all along that where the rubber is.

[Joco]

Finally took the plunge this weekend and surfaced the mag-chuck.   Here is the sequence of photos from the start with the pencil lines in place through to the final sparked out surface with a total of about 0.08mm taken off.

General approach was to touch off on the known high spot in the top left corner then work across with the magnets engaged.  Also using coolant the whole time to keep all the heat at bay as well as keeping the amount of dust to a minimum.

Took a while but hopefully worth it.

Cheers - J.

[Joco]

In between other jobs I managed to squeese some shop time to do a test piece on the newly surfaced mag-chuck.  This is just a mild steel block 40x80mm  which I have been using.   Wasn't shooting for any particular thickness in this test, more to see how consistently across the part it was grinding the thickness.

The overall  thickness ended up being 13.278mm.  The corner that is showing 13.277mm is just on the cusp of being 13.278 as depending on which way I hold my tongue I get 277 or 278.

Upshot is the old girl looks to be delivering within 1um, which for the type of work I get into is awesome.   

[Admiral_dk]

Fantastic result -you should be dead chuffef with that result 

Per