Seeking help from experienced Crankshaft Grinders

I recently aquired an old Storm Vulcan model 14, the predicessor to the very common 15. Although old, it had little use, and the price was right. After dissassembly, cleanup and reassembly, and tweaking it in, our biggest problem is that it is turning journals .0005 out of round.

My machinist has quite a bit of crankshaft grinding experience, and we also have the original instruction and trouble shooting manual. Most common cause for out of round condition according to it is too much steady rest pressure. But that is not our case here, we have tried just about everything. New bearings, although I didn't think that was the cause. The headstock and tailstock have new wear shims under them, and we have spent quite a bit of time lining them up using the adjustment set screws.

The out of round is very consistant- always there, always right at .0005, and for both rods and mains.

Anyone have any ideas or something that we may have overlooked?

Thanks-Hanz

How does the dresser operate?

John

Dressing the wheel and keeping it dressed is vital. Got any spindle run-out?

Dresser clamps to the front bed, same as the headstock and tailstock clamp to.

The wheel dresses nice, we have only turned a few dozen journals of our test crank, and have dressed it a couple times.

Don't know about spindle runout, we will check that, although I would think that dressing the wheel would compinsate for that. Machinist says that all of the out of round condition are on the same axis, in other words on a 5 main crank, the high sides would all be in a line, as well as the lowsides in a line 90* from the high sides. I will check this myself just to make sure I am getting good info.

Hanz

Is this a belt driven workdrive? I have no experience with this particular grinder. However, on other machines, I have seen mismatched, bad, and/or loose belts cause similar problems. As can bad and/or loose workdrive bearings. Are the machine centers themselves in good condition? Even the workdrive motors can occasionally cause problems like this.

Hanz,

I have had some shafts that will be .0003"(the limit) out of round, and nothing I try helps.
The next shaft will be almost perfect ( or as close as I can get them!).
Have you tried more than one shaft?

Since the high sides are in a line,if there is no play in the head and tail stock bearings,it could be the shaft itself.

You do have the counterweights set right?

Oh,btw,I have some wheels and hubs stored here for a 15.
If they will fit,I'll ask the man they belong to what he wants for them,if you need any!
Regards,Robert.

Robert-

We had it dialed in to .0003 out of round on our test crank, went to grind a job crank, and it went up to a full .001.

Our latest theory- the tailstock assy seems to be running out. The bearing bore seems to have been sleeved, not sure if this is factory, but doubtfull since it does shows signs of being 'worked on' before. We are going to resleeve it this week, making sure it is square to the slide surface.

As far as the wheels, let me know what sizes, quantity, and price, as we also have a 15. Thanks-Hanz

Oh, what do you mean by counterweights set right? We had it in balance (rod throws) and the manual says to use twice the weight at the headstock than the tailstock. Does this sound right? BTW it was the #1 rod that was so far out of round.

[This message has been edited by Hanz (edited 08-15-2004).]

Hi Hanz,
Sorry I haven't been back soner,but I'm right in the middle of three engines!

Anyway,
"We had it dialed in to .0003 out of round on our test crank, went to grind a job crank, and it went up to a full .001. "
Sounds about my luck!

As old as the machine is,unless it was in a one moan shop,I would think i would have had some rebuilding done to it.

I'll make myself a note to call my tool dealer about the wheels and hubs,and to see if he can help.

I was refering to the counter weights.
My machine manual advises to set the weights equally,but it is a newer machine from a different company (Zanrosso/Kwik Way/Winnoa VN)

Is that a center or chuck machine btw?
I'm thinking center problem if it uses them instead of chucks.
I'll try to get back to you a little sooner!
If you want to take this to email,it is in my profile.
Regards,Robert.

After doing a "search" on crank grinding I found this old post. Wondering if Hanz ever figured out his problem? I just aquired a 1962 S/V 15A and am comencing to learn. One thing I read in the instruction manual was the wrong type of wheel (material) can cause that kind of run-out.

IF THIS WERE BEARING RUNOUT, the .0005 would not be in the same place all the time. (Sorry, I didn't mean to shout.)
If the .0005 is there all the time and in the same place, I would be looking at a bent spindle or if it is a belt drive work head, Look for a too tight belt and or runout in the driving motor.
I have found runout caused by even a bent shaft running against the spindle shaft.
Run a piece, leave it chucked up and put the indicator to it. Indicate where the grinding wheel is contacting the work and then indicate 180 degrees from point of grind. See if the readings compare. If you have nearly zero at the point of grind and the full .0005 at 180 degrees, I would look for something pushing the spindle shaft and or a bent spindle. If you have a little runout at point of grind and about double at 180 degrees, you have bearing runout somewhere.
I would hope after 3 or so years, you have solved the problem. I bet some people would like to know what the problem was and how you solved it.
Regards Walt...

I am working on this same problem. I haven't solved it yet, but here are some thoughts. My machine is a 15 and I am currently running two chucks, but I may try it without them.

The troubleshooting in the 15/15A manual gives the following for "Work out of round":
- Expansion of work - Keep temperature of work down by using more coolant and lighter cuts.
- Work out of balance in machine. - Correct with counterweights.
- Faulty operation - Use less steady rest pressure.

I also thought I saw somewhere loose spindle bearing nut. After this, I tightened mine to 15 lbs.. Everything seems good at that torque, it would be nice if someone had the correct specification (SV15).

I don't believe my problem is work expansion, and I have played with the steady rest pressure enough to eliminate that.

Right now I really believe it is probably a balance issue. The 15 does not use a screw style counterweight. It uses a few counterweights which the operator selects and bolts on the head. In my case, I have it balanced neutral with respect to putting twice the weight on the headstock as the tailstock (instructions in the manual). If I am experiencing a balance related problem, I don't see it in that aspect of the balance. I am looking at the sleeve in the tailstock. I notice my spindle lock is not screwing and it has been over tightened. I will clean it up so that it is more likely to lock the spindle in place and try again.

Put some test indicators on the tailstock sleeve, anchored to a stable part of the machine. See if you get the needle rocking back and forth as the crank rotates. Try moving the contact point around the tailstock and on other parts of the machine looking for movement that shouldn't be present.

This only works if the indicator base is on a solid, non-moving part of the machine. If you take some pictures of the setup and post them here we may be able to give better advise.

The tailstock sleeve is not exposed for testing.

I have increased preload on both spindle bearings. The description is to preload until a slight drag is felt. I used a fish scale to turn the head and tail stocks until it took a couple of extra pounds to move them, The tail stock initially took virtually no pull to move the head stock took about 4 lbs. to rotate. To get that type of resistance, the bearings were torqued to about 30 lbs. It did not make a big difference if any.

The "out of round" is in an oval shape.

I put new bearings in both the head and tail stocks. Most of the bearings that were in them were SKF 6208-2RS1/C3. I am wondering if they may not be a tight enough bearing and perhaps I should be running a tighter tolerance bearing like a C2, or maybe because they are preloaded, it would not make a difference.

I tried turning on centers, but it did not seem to make a difference.

We see this problem when we try and grind with a chuck on the Head stock and a center in the tailstock. It could be a balance problem like you said. If you try weights and it does not work then your head and tailstock are not lined up. The chucks have to be running parallel to each other within a .0001 or .0002. The center heights could be bad also. The Headstock could be higher than the tailstock or the other way around. Look at trying to get this lined up.

Hanz said:

I recently aquired an old Storm Vulcan model 14, the predicessor to the very common 15. Although old, it had little use, and the price was right. After dissassembly, cleanup and reassembly, and tweaking it in, our biggest problem is that it is turning journals .0005 out of round.

Anyone have any ideas or something that we may have overlooked?

Thanks-Hanz

Click to expand...

Hello Hanz: Before i give you my 2 cents, i would like to ask a couple of questions if i may?

First off, I ran one of these for many years, many years ago, and never experienced this problem.

Next, Did you do a test grind before you purchased it?

If you answered NO to the test grind, then you inherited a problem. If you answered Yes, then you answered your own question, in your disassembled, replaced, and tweaked statement, (imo).

In my opinion, you may have an out of round bearing, which should have show have shown up on your alignment and test procedures.

Test: Mark and remove the bearing, and turn 90, or 180 degrees. Then test grind again, and see where the high spot falls, if indeed it does.

Please Post photos of your grinder and the results of the out of round grind.

Good Luck!

I managed to solve my run out problem. Loose head and tailstock bearings. That is also why it looked like a balance problem.

The manual suggest "preload until a slight drag is felt". That is a difficult thing to determine. I used a fish scale to help me, although I never got a reading past about 1-3/4 lbs.. I would tighten the nuts about 1 or 2 lbs., then grind a set of mains and repeat again. I currently have about 45 lbs. of torque on the nuts.

The difficult part is you have to build some kind of wrench to allow you to use a torque wrench for this to mean much to you.

I found that after tightening and grinding the bearing would seat in, and loosen a bit.


Now hopefully my last problem is getting an even face when dressing my stone.

Initially, I was not flooding my stone while dressing. I am now, but when grinding the crank, I still have a difference of 0.0005" difference, roughly. I have shortened the length it protrudes from the mount.

A follow up.

I am not up and running yet. I can grind the mains on centers, but when I put on the chucks it isn't good enough. And, when I go to the throws my out of round returns.

I suppose this could indicate that I still don't have my head and tail stock bearings tight enough to deal with the extra weight of the chucks or an imbalance when offset.

I played with it a bit more, I set up a dial gauge on the head and tail stock, and pressed down with several pounds pressure and got no indication of flexing.

I revisit my balancing, and decided I had over balanced the shaft by using fish scales to lift on the far and near side of the head and tail stock. I had a 13lbs. weight on the head and a 7 on the tail stock. I went to a 7 on the head and a 5 on the tail stock (sbc 283 crank of course). That seems closer to balance.

It seems to be cleaning up most of the out of round on the rod journal. By taking it to +0.0005" of target, I am getting to within .0002-3" of round by pushing it with the steady rest. I would like to get closer, but I don't know if I should expect to with the SV15. This is on only one throw so far, I will have to see how I do as I try the end throws.