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Grockel grinder - truing the ways

PassNCrash

Plastic
Joined
May 2, 2019
I am going to “true” the “ways” on my grinder.
The ways are 11-1/2’ long, about 1-3/8” wide and about 20” apart. The head travel 8’.

First I need to assess accurately just what I have.
Then I need to make corrections.
I would like to map it out about ever 1 inch or so.

So – how do I do that? I don’t think levels alone will tell me enough.
I don’t think piano wire is accurate enough, but it is an option.
The only thing I can think of is some form of laser or optical device.

Of course I would like it to be as accurate as possible but I think I would be happy if I could get it to within 0.005” over the full length. A small deviation over the full distance is tolerable. Small bumps and dips in a short distance are not.

Then how do I correct it. Is this doable by scraping? Perhaps a temporary rail trolley setup to move a grinding head over it.

I will add a picture if I can do that as a new member without prior posts.

It is a Gockel G30 with a 10HP head.
The ways are covered with a strip of spring steel. The head rolls on 4 steel rollers.
The ways are steel not cast. They have developed a small crown across the width.

I know there is lots on information I am not including here but did not want to make it too long.
I need to be able to do this with only putting it out of service for a week at a time. Could be multiple times.

If there are short low spots could I fill with Belzona product or something.
I am not a machinist but was an industrial mechanic.

I can spend a few thousand for gear but not much more.

Thanks
 
How old is this machine?

To be clear, which way are the ways/rails crowned? Along the length or across from front to back?

The only trouble that I have ever encountered was rust and grit under the wear strips. We would occasionally pull up the strips and stone the rails, coat with oil, and re-tension the wear strips. We have had to replace the wear strips but never had to touch the rails.

These Gockel machines are weldments. You can twist and raise/lower them easily at the mounting pads.

If the rails are indeed worn then I imagine that the grinding head slide is shot also. They get sloppy especially if it is an old machine. There is not much there to keep the grit and coolant out of the head ways.

The carriage rides on four bearings as you said. Also, there are four that ride underneath the rails, and there are inboard bearings.

I cannot remember if the rails are screwed or welded on. If fastened, then they can be removed and surface ground. If not, since the grinding head/carriage is relatively easy to remove, the whole base can be sent out for grinding.

Gockel did not scrape the rails, they were ground.

There is a member on this site named CASH. He would have more insight.

Bill
 
A temporary rail trolley or the grinders trolly if the rollers are still good might hold an indicator to strike the chuck off to one side where it got little or no wear. Yes looking for how straight a path not a long taper because the whole chuck may need to be tilted.
I dont know how the rails are attached.The wear strip might be considered perhaps just doing them.
Should get it to better than .002 IMHO

Might set a straight edge on the chuck and shim it dead straight then indicate.
 
Hi,

Good questions.
How old - old - near as I can tell about 1968.
Rail crown - this is across the width (1 3/8") - I was a little surprised by this, the wheel must have convex wear - have not checked.
Welded - yes this machine is a weldment. Do you mean you can actually twist this machine with the jacking bolts. There are 6 of them.
When I set the machine in place and leveled it I could not detect any twisting as I leveled it. It seems like a pretty sturdy beam.
Head slide - yes other items need attention. Most of those I think I can deal with. Straightening 12' rail is not so obvious to me.
Carriage bearings - as you discribe except this machine does not have any "holddown" rolls under the rails.
I wish the rails were screwed on - no luck - welded.
I will be removing the entire carriage but sending out the base (est 4000/bs) is not an option for me. I have to do whatever in situ.
Scraping - I was thinking more in terms of how to remove metal not so much surface finish. If grinding is doable I think that would be more practical.

Any thoughts on how to accurately assess rails?

Thanks
Glen
 
Hi,

Good questions.
How old - old - near as I can tell about 1968.
Rail crown - this is across the width (1 3/8") - I was a little surprised by this, the wheel must have convex wear - have not checked.
Welded - yes this machine is a weldment. Do you mean you can actually twist this machine with the jacking bolts. There are 6 of them.
When I set the machine in place and leveled it I could not detect any twisting as I leveled it. It seems like a pretty sturdy beam.
Head slide - yes other items need attention. Most of those I think I can deal with. Straightening 12' rail is not so obvious to me.
Carriage bearings - as you discribe except this machine does not have any "holddown" rolls under the rails.
I wish the rails were screwed on - no luck - welded.
I will be removing the entire carriage but sending out the base (est 4000/bs) is not an option for me. I have to do whatever in situ.
Scraping - I was thinking more in terms of how to remove metal not so much surface finish. If grinding is doable I think that would be more practical.

Any thoughts on how to accurately assess rails?

Thanks
Glen

What keeps the carriage from lifting?

This one is older than any I have dealt with. I think the oldest was 1984.

I would start with contacting Gockel first. See what they have to say.

Bill
 
I am very familiar with these style machines, reform, gockel, toyo. Many of our wood industry customers have them and I will go into their facilities and perform maintenance, grind in their magnets and help with wheel selection.

Feel free to PM me if you would like to talk.

In your area is Akhurst Machinery, they sell Reform but I assume they would perform maintenance on any brand.
 
How to assess the rails? I am not familiar with these machines. But I know of two ways to accurately map out 12 foot long ways.

One way is to use an autocollimator with a fixed light source mounted on the machine, and a mirror on the traveling part or on a slider that moves along the way. A two-axis autocollimator will let you map out the straightness in both the vertical and horizontal directions. A good autocollimator will let you measure to 1/10 of an arcsecond, which is corresponds to 70 millionths of an inch deviation over 11.5 feet.

The second way is with a pair of precision differential electronic levels such as a Taylor-Hobson Talyvel 3, 4, 5 or 6. You leave one head parked at the end and move the other head along the way. This only measures the vertical deviations, but is easier and less fussy than the autocollimator, and provides similar accuracy, around 0.1 or 0.2 arcseconds. For a knife grinding machine with square flat ways this should not take more than a few hours. You move the level along the ways in steps of 3 or 4 inches, recording the angle at each station. Adding up the differences and subtracting the linear trend gives a graph of the deviation from a straight line.

It is smart to do some careful measuring before you start removing any metal.
 
Last edited:
Thanks for all the good info.
A few replies and more info.
- What holds the head down - nothing mechanical, just the weight of the head - estimate 300lbs.
I do find myself wondering somethings if I take too heavy of a downfeed if this is an issue, but does not seem to be.

I should have spelled out a little more clearly that I am a small operation and can not afford some of the better methods that would give great results. I spec'ed out a laser system but it's about $40,000.00. Even renting(with shipping etc.) was more than I want to spend.
Also I am on an island so everything is a ferry ride.
Transporting the unit is out of the question.
Accuracy of the work coming of the grinder meets spec. but I know it could be better so I and want to do this before issues arise.
So I guess I am looking for good accuracy for a moderate cost. I don't need 0.0001"
Do you know of anywhere (Canada) to rent a autocollimator or Taylor-Hobson?

Thanks
 
Honestly for the numbers youre talking I think a 10sec level would be more than enough, be sure the bed isnt moving as you traverse the head. You could ride the level on the head inline with and across the ways to give a decent idea of twist and global condition of the ways, every foot would be enough for that. You could look for local holes with an indicator mounted to a 123 block riding the way, indicate right next to the block, could also keep an eye the level for sharp local movement. If youre concerned about the horizontal number I think a taught wire should work fine, failing that you could mic over the gibbed sliding surfaces, should be pretty close to zero the length of the bed if its in decent shape.

Could scrape the bed easy enough as long as its not too hard, its box type ways isnt it?. Something like this?
Gockel_G50_Rsel_Grinding_machine_for_knives_1410928232_big.jpg

Id think it would be one of those occasions where you want to finish it up with a very low depth of cut as the head uses rollers.

Cheers
D
 
Thanks for posting the picture Demon73. Yes that is very close to what I have. Mine little older and maybe a bit wider probably a lot heavier.
It clearly shows what I was not great at describing in words. The main thing being the 2 long "ways" with spring steel wearstrips.
Can not tell if yours are removable but mine are not.
By a "10 sec" level I take it you mean a Starrett 199Z type level or similar. I have a 98-12 but would be willing to buy a 199Z for this.
I think I understand most of your comments. I think I will order the level.
I have been wondering if "stepping" a accurate level along the ways would be practical or I am asking to problems with compounding errors by walking a level over 12'. Maybe if I used two gauge blocks under the level and string 12 point together.
If I was to attempt to scrape the ways does anyone know of a source for a 3' or so long granet pallet than I could lay on the ways to blue the high spots.
As you know the head rides on wheels so it will not span any low spots so I have to be very careful not to create any.

Thanks
Glen
 
I think you would be better off to remove the spring steel strip, remove the ways and have them sent out to be ground.
 
I would start with removing the spring steel wear strips
You say they cannot be removed? I say they can

Then level the whole thing again and replace the spring steel
Then see where you are
Also keep in mind that the accuracy of the work also depends on the tilting magnet or clamping beam
The grinding head needs to move parrallel with the clamping beam tilted at the requiert angle
Straigtness is of less concerne as the knives beeing ground are flexible enough if the straightness is off graduatly


Peter
 
Yes of course the wear strips can be removed. I have a set ready to replace them.
The wear is not the wear strips, it is the "ways" the wearstrips sit on.
They are NOT removable.
There are no other issues concerning me other the the wear on the "ways"
There have been some good suggests on accurately assessing the wear.
Unfortunately they are a little pricey.
I am going to purchase a 199Z Starrett to assess the wear then rig up some temporary straight edges and build a grinding sled to ride on them.
Open to other suggestions for assessing and grinding the ways nice and flat.

Glen
 
Reform grinder ways

I am going to “true” the “ways” on my grinder.
The ways are 11-1/2’ long, about 1-3/8” wide and about 20” apart. The head travel 8’.

First I need to assess accurately just what I have.
Then I need to make corrections.
I would like to map it out about ever 1 inch or so.

So – how do I do that? I don’t think levels alone will tell me enough.
I don’t think piano wire is accurate enough, but it is an option.
The only thing I can think of is some form of laser or optical device.

Of course I would like it to be as accurate as possible but I think I would be happy if I could get it to within 0.005” over the full length. A small deviation over the full distance is tolerable. Small bumps and dips in a short distance are not.

Then how do I correct it. Is this doable by scraping? Perhaps a temporary rail trolley setup to move a grinding head over it.

I will add a picture if I can do that as a new member without prior posts.

It is a Gockel G30 with a 10HP head.
The ways are covered with a strip of spring steel. The head rolls on 4 steel rollers.
The ways are steel not cast. They have developed a small crown across the width.

I know there is lots on information I am not including here but did not want to make it too long.
I need to be able to do this with only putting it out of service for a week at a time. Could be multiple times.

If there are short low spots could I fill with Belzona product or something.
I am not a machinist but was an industrial mechanic.

I can spend a few thousand for gear but not much more.

Thanks

I can not see any response as to how you made out on this? Do you or does anyone have a supplier for the strip steel used for the wear strips??
 
inexpensive way to rough find is to take a straight edge. Perhaps just the side of an aluminum level likely to be <.005 error to straight in 36". set it at worst low place and see dish. Place shims to make it level. next place the level from the shim stack and level it to one side again. Shim up and level off again. that likely will get you to end of the machine...This will give you a rough idea of total error and help decide what to do.

Time on 144"+ grinder will be expensive. Simple flat grind will be less. You also have to check the part holder to see if it is flat or wore out. Plastic way material is not difficult to scrape but you likely need a precision straight edge to do that.
 
replacement way (g50) at gockel america how do they install those pin to insures that the way don’t slide on the rail and create wear
 








 
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