Author Topic: Ingar-RT618 Surface Grinder (Boyar Schultz clone)  (Read 5142 times)

Offline john mills

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Re: Ingar-RT618 Surface Grinder (Boyar Schultz clone)
« Reply #15 on: August 05, 2020, 11:05:48 AM »
you say you get a better wheel dress with a small single point diamond ,what were you trying before . I would think it is more important to have a sharp corner the size needs to be big enough to hold together in its mount .
when i ground crank shafts the wheel was quite hard to hold the corner radius the diamond needed to be a good size Repco i worked for in there book on engine reconditioning say the diamond for that purpose should be
3  to 5 carrots  at one time the forman lost my diamond and got a replacement which was far too small all i did was grind flats on the diamond .for your smaller machine smaller would be fine  the main thing is to keep positioning the point so to keep a sharp corner the size should not matter it depends on what you can pay for.
i am no expert on diamonds i don't know if there are different  grades .bigger should not matter as long as you can keep wearing a sharp corner to use an it holds it shape to get the wheel dressed.
     John

Offline nj111

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Re: Ingar-RT618 Surface Grinder (Boyar Schultz clone)
« Reply #16 on: August 05, 2020, 11:22:34 AM »
I think it was previously around 1 carat dressing a 1/2" wide wheel 8" diameter for the Jones and Shipman.  I must have read somewhere not to use too large a diamond, I forget where though!  If you've been grinding crankshafts then you will most probably have forgotten more than I will ever know about grinding!  Good to have your input here John.
Nick

Offline john mills

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Re: Ingar-RT618 Surface Grinder (Boyar Schultz clone)
« Reply #17 on: August 05, 2020, 01:53:35 PM »
Yes i have forgotten a bit but this reminds me of have that problem of the diamond being too small to work the smaller diamonds have been ok for these smaller wheels .i worked a work shop for a long time were i also used a jones and shipman cylindrical grinder ,it was what i would call a small machine the wheel 10 or 12 inch dia and 1 inch wide from memory it was a bit sad it had been used for production but it worked ok and was handy for grinding tooling for working with wire .wire guides and pins and rollers hard tool steels.it only had a smaller diamond for wheel dressing .               
                      John 
« Last Edit: August 05, 2020, 01:56:38 PM by john mills »

Offline Joco

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Re: Ingar-RT618 Surface Grinder (Boyar Schultz clone)
« Reply #18 on: August 07, 2020, 05:07:40 AM »
The original owner for this was a great old chap.  He kept EVERYTHING.   Here's a page from the brochure that has the spec's.  My model being the manual version of the 618.

James
Wellington - NZ

Offline john mills

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Re: Ingar-RT618 Surface Grinder (Boyar Schultz clone)
« Reply #19 on: August 07, 2020, 07:51:28 AM »
bringing back memories   these parts  i have seen these parts before .it would be more than 20 years  since i left that factor but it had
simllar problems on that same machine , the belt had failed  the pulley was damaged.they could not get a replacements  .so replaced the pulleys   and  belts with ones they could get .
        John

Offline Joco

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Re: Ingar-RT618 Surface Grinder (Boyar Schultz clone)
« Reply #20 on: August 07, 2020, 09:01:18 AM »
John - looks like its a standard J6 profile poly-v belt.  Should be a 279mm but 280mm seems to be readily available (getting one as a spare). The new pulley should be good for another 40 years I hope.  :-)

James
Wellington - NZ

Offline Joco

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Re: Ingar-RT618 Surface Grinder (Boyar Schultz clone)
« Reply #21 on: August 08, 2020, 11:15:45 AM »
Have built the balancing ring which was quite fun. But not convinced I'm getting any better finish than before.  Some more tests I think.
James
Wellington - NZ

Offline Joco

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Re: Ingar-RT618 Surface Grinder (Boyar Schultz clone)
« Reply #22 on: August 19, 2020, 08:45:20 PM »
Still investigating and reviewing.  The latest is:
- tried to get the original coolant pump working but bad bearings ended up in it drawing excessive current and burning out the windings. So have replaced it with a new single phase pump that is awesome.  25 litre/m and near silent operation.  Being single phase also makes the wiring significantly simpler. Remember, no 3 phase in the shop.

- mapped the table using a 10 micron DTI. The indicator was mounted on the spindle column as the fixed reference. You can see from the picture it is pretty consistent left to right in each measuring strip but as I moved from the front to the back i got a 0.4mm rise! Which is  huge.  I have done a couple of quick sweeps front to back using the table top as the reference point and that seems to be within 0.01mm. So ... there is something wrong with the saddle and how it is travelling.  I find it hard to believe there is 0.4mm wear on those ways. Given that level of movement its almost like something is riding up. Guess I am going to have to pull things apart and take some measurements.

Cheers,
J.
James
Wellington - NZ

Offline Admiral_dk

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Re: Ingar-RT618 Surface Grinder (Boyar Schultz clone)
« Reply #23 on: August 19, 2020, 09:06:36 PM »
I hope that you discover the reason for the .4mm discrepancy and that the solution isn't too big a problem / cost.

Offline Joco

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Re: Ingar-RT618 Surface Grinder (Boyar Schultz clone)
« Reply #24 on: August 23, 2020, 04:36:31 AM »
The investigation continues and I think I have found the source of the 0.4mm issue on the table.

I pulled the table and carriage off and started some basic mapping of relative heights from various reference points.  I was looking for large variations but the process gave me some visibility of where I am going to need to eventually rework the machine to recondition for wear.

So, going down through the images ...
[1] Mapped out the base ways and typically got no more than 0.01mm in variation from the reference points.  So while some wear nothing out of the oridinary for ~40 years of age

[2] flipped the carriage over and inspected the underside. This was the next potential culprit.  At least I could see some of the flacking pattern still.  But it will want some TLC at some stage. 

[3 - 4] The mapping of the carriage underside.  Again typically nothing over 0.01mm in variations. So some wear but nothing unreasonable or unexpected.

[5] I put the carriage back on and used a DTI following along behind the carriage (and referenced on the carraige) to see if at some point the carriage was rising on up something.  across the entire travel which is the bulk of the Z axis total travel I go a delta of 0.01mm on that reference surface (which is actually one of the central ways).  So no raising up issue either.   At about this point I started to develop a suspciion on what the issue might actually be.

If you go back to post #5 and look at the tear down pic #4 you can see the table ways have a teflon coating. I would guess essentially like Turcite. I started to wonder if the geometry of these ways had the table in a proper plan in the front to back direction. i.e it was lower in the front than the back.  This could have been caused by wear OR a reconditioning job of that material that was not done correctly and left the front way low.

IF I was correct then the shiming would result in a paralley surface as the table was not rising and loweting it was just permanently set at an angle front to back per above musings.  So ... to test.

[6] I used a couple of metric 123 blocks.  One with no shim had a 0.27mm raise from front to back over its 75mm length.  I then shimmed the other with about 0.26mm shim stock (I originally thought it was 0.28mm) but later remeasuring after the photo showed it was not that much. That shimming resulted in an error of 0.01mm over the 75mm length.  The clamp was to overcome a tendency for the shim stock to spring the 123 block up and give bogus readings.  Once clamped I started to get some consistency.  Anyway, I think this test has proved my theory about the geometry being off.

I have since gone on to place the mag chuck back on and play with some shims.  I need to some some more shim stock so I can get a better contact area and a closer lift.  I'm not keen to take 0.4mm off the table. I would rather do it properly and re do the telfon running material and scrap it in properly.  But I need to learn some basic scraping skills first. I guess I could take 0.4mm off the mag chuck bottom and flatten it later.  It has plenty of meat on it for such an exersice at a later date.  I shall see how I go on the shimming and if I feel I am getting ok reults from that.

It's been a good exercise in surveying the state of the machine with lots of photos of measurements along the way.  I now know where the skeletons are and what level of reconditioning work I will face in the future.


Cheers,
James.
« Last Edit: August 23, 2020, 04:42:11 AM by Joco »
James
Wellington - NZ

Offline Joco

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Re: Ingar-RT618 Surface Grinder (Boyar Schultz clone)
« Reply #25 on: August 24, 2020, 01:22:39 AM »
Had a quick play over lunch putting the mag chuck back on and using shims made from soda cans.  2 x stacks  of long (~150mm lengths) of 3 shims under the front foot of the chuck.  80% of that front foot is now sitting on a shim stack.  I'll also wedge some in under the clamping points so that do not over stress.  Anyway, the point being I did a quick mapping.  wow - I think, as a stop gap measure until I can address the underlying geometry issue, this looks to be a winner.  Check out the pic of the mapping.

Worst error is in the back left at 0.04mm difference compared to the master front centre reference point.  Then a few 0.02mm ones but the bulk are all +/- 0.01mm.  I think give the chuck a light dusting and this will be nice and flat.

Cheers,
J.
James
Wellington - NZ

Offline john mills

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Re: Ingar-RT618 Surface Grinder (Boyar Schultz clone)
« Reply #26 on: August 24, 2020, 02:54:52 AM »
is the surface the table sits on flat    then is the mag table parrell .does the table travel smoothly .

if when you shim something on the table flat does it travel flat .
if so i would grind the table flat  then the base of the mag table  but careful shining so it is not distorted as it is clamped down .then mount the table in its position and regrind the top surface .the table may not have been ground on that machine  if the slides are reasonable it should grind parallel to the table .just shimming may not have the mag table sitting flat and it move between the shims or hollows in the machine table top face depending on what is on the table when th chuck is turned on.

         John

Offline Joco

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Re: Ingar-RT618 Surface Grinder (Boyar Schultz clone)
« Reply #27 on: August 24, 2020, 10:52:22 AM »
Thanks John.

is the surface the table sits on flat
Hard to measure as the ways the table runs in are a V and flat combo.  So not sure where the common plan would be.
Quote
    then is the mag table parrell .does the table travel smoothly .
The table travels pretty smoothly what from I can tell.  I'm not sure what you mean by the mag table is parallel.  You can see the mapping pics so those are the measurements I have after doing a test shim.

Quote
if when you shim something on the table flat does it travel flat .
Yup it does seem to be pretty flat.  Have just done some more work on that tonight and finalised some shims that get the chuck pretty dang close over its total surface.

Quote
:lolb:if so i would grind the table flat  then the base of the mag table
It's the 0.4mm I have been leery about removing.  But while seeming a lot is that not too much of a real problem?  I very new to surface grinders and don't know what would be seen as acceptable.

Quote
but careful shining so it is not distorted as it is clamped down .then mount the table in its position and regrind the top surface .the table may not have been ground on that machine  if the slides are reasonable it should grind parallel to the table .just shimming may not have the mag table sitting flat and it move between the shims or hollows in the machine table top face depending on what is on the table when th chuck is turned on.
Yup - very conscious of those concerns hence doing lots of checks with chuck on off and will do some checks with some parts clamped to the active chuck.  Appreciate the input and interested in advise so I can learn.

Cheers,
James.
James
Wellington - NZ

Offline john mills

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Re: Ingar-RT618 Surface Grinder (Boyar Schultz clone)
« Reply #28 on: August 24, 2020, 01:03:23 PM »
if you grind the top of the machine table would it take of to .4 on one side ,if that would be close and be just cleanup  .if you fit the table would it grind more of one side  the .4?
if you grind across the surface doe it come out flate  or a series of steps.
john
« Last Edit: August 24, 2020, 01:10:55 PM by john mills »

Offline Joco

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Re: Ingar-RT618 Surface Grinder (Boyar Schultz clone)
« Reply #29 on: August 24, 2020, 07:51:38 PM »
John - based on the tests I have done I have observed the following:
  • the table has a linear rise from a zero reference at the front up to between 0.38mm to 0.40mm at the back
  • these measurements are pretty consistent from left to right. There are few extra high spots at the far left and right
  • I had placed the chuck on the table without any shims and ground some test pieces. The grind would start at the back of test piece where i touched off and would only do a few mms before the wheel was too high, reflecting the slope in the table. I would then lower the wheel and repeat the cut lower process until having gone all the way across. Each cut was smooth. There was no stepping. The grind seemed to be smooth in its progression from front to back. This also means if I was to grind the chuck with no shims it would behave in the same manner. Given I am dressing the wheel under this setup I would assume I am essentially putting a matching angle on the wheel face.
  • when I originally took the mag chuck off the table it had been shimmed in the front by the previous owner.
  • I have been wondering if i leave the table as is. Put the chuck on mag side down such that I take the correct slope off the bottom to match/compensate the table such that when put back on the top is pretty level like when shimmed. And all it needs is a light dusting.

Cheers - James.
James
Wellington - NZ

 

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