Thread: Noisy Spindle - Hercus Model O

Hello Greg,

I am unsure as to the cause of excess pulley end play. It has been a while since I removed my spindle and it was not straight forward, due in my case, to a partial seizure of the pulley on the spindle. Your machine looks like a 3 tee slot table late model which differs in a number of ways from the older 2 slotters.

The horizontal spindle draw bar extends the full length of the spindle. There should be nothing else inside the spindle bore other than the 3 Morse taper of the horizontal arbor. I use a 19mm diameter solid aluminium bar drift to remove my arbors from both the vertical and horizontal spindles. The 3C adapter should simply tap out.

Read the old posts (if you have not already done so) regarding the incorrect use of grease in the oil nipples.

BT

Greg
I just checked my model O mill & its also got .009 " clearance between the cone pulley & the gear on the main spindle.
However it does run smoothly & does not make any noise.
Perhaps the drive pin in the back gear is worn. Mine is a somewhat loose fit but does not cause a problem.
So I cannot offer a solution to your machine. I agree with Bob, its very important to use oil only not grease.
My machine is the 2 tee slot version.
regards
Bruce

Thanks Bob and Bruce,

I have been able to remove the collet adapter. I just needed to be less gentle! I still haven't been able to move the arbor but at least I know now that it will move eventually and there is no drawbolt involved.

Thanks Bruce for the advice on the clearance. It seems that the clearance I have is not the cause of the noise. As I said earlier, I can see the cone pulley physically moves along the spindle each rotation. It is not clear to me why it would move sideways.

Greg

Greg,

I had a hell of a time trying to remove the horizontal arbor when I first acquired my No. O. I ended up making a puller from some 12mm steel plate. I bored a 1 1/16 " hole in the plate to enable it to slip onto the arbor and fixed the plate using the arbor spacers and nut. The plate was tapped to accommodate a pair of 1/2"W bolts. The bolts were screwed up against the body of the mill and progressively tightened while I belted the drift from the rear of the machine. It worked. I can draw something if my explanation has failed.

Bob.

Bob,

Yes I understand what you did and that seems to be a good way to reduce the force of the imact on the bearings, while increasing the overall force on the arbor. I will give that a go. Thanks again.

Greg

Greg,

Some more thoughts. Does the pulley make the same racket with the back gear engaged? If the locking pin is the source of the noise, it will abate in low gear. Also, is there any play in the fit of the bull gear on the spindle key?

Another disconcerting source of noise in the 2 slotters is loose screws on the Tufnol countershaft gear. I don't know if this feature was retained on your model.

Popping the spindle out is an easy thing to accomplish with a block of wood and a hammer. Could be worthwhile to ensure that the oil passage in the pulley is free of grease. It would also allow you to check the bearings and set the correct bearing preload on reassembly.

Bob.

Bob,

I forgot to mention tha the noise is slightly less when the back gear is engaged. It could have something to do with the lower speed though. Not sure.

I will check the countershaft situation and the fit of the bull gear on the spindle key tomorrow when I look at it again.

The more I think about it, it seems best to take the spindle out. I can check the things you are suggesting much better if I do that. As long as I can move the bull gear off the spindle as I move the spindle out of the casing, it should be straight forward. I don't have the pulley siezure complication you had with your machine. Ideally, I would like to get the arbor out of the spindle before I do that... I need a bit of time to make up the tool that you suggested to help remove the arbor.

I will see how I go tomorrow.

Greg

Bob,
I took the spindle assembly out today and found that there was significant wear and galling to the spindle and the cone pulley. The spindle measured 41.21mm OD and the pulley measured 41.68 mm ID. The pulley was quite a sloppy fit on the spindle! I am sure that was the source of the noise. The assembly had been maintained with grease during its life and this may have been a problem as indicated by you and Bruce.
I have taken the spindle and the pulley to a machinist to fix as I don’t have the time right now. He will bring the OD of the spindle down to about 40 mm and bush the pulley. A new pulley spacer will need to be made and a new retaining nut for the back end of the spindle will need to be used. A new bearing on the front and back of the spindle will be needed with a smaller bearing ID on the back end.
Thanks for your help.
Regards,
Greg

Greg,

It may be too late but here's another idea. The 2 slotter pulley appears to be the same as that of the Hercus 9" lathe. "Australian Metalworking Hobbyist" run by Mal, one of the forum members, may have a replacement pulley. Australian Metalworking Hobbyist

The idea of reducing the diameter of the spindle and the associated work involved seems complex. Is the intention to sleeve the pulley with cast iron? Could the galling be removed without a large reduction in the spindle diameter, relying on the sleeved pulley to accommodate the wear? This may remove the necessity for a lot of the additional work.

I stoned off the high spots on mine and reassembled it.

Hercus used S1045 "Duraflex" for their spindles. I can't recall if mine was ground all over, but I would hazard a guess that it was. The galled spindle scored the pulley bore in a number of places but I considered there was enough viable bearing surface remaining to ensure proper running clearances.

I have had no trouble with my spindle since the "glitch". I ensure that the pulley is adequately oiled.

If you found grease in the pulley, it may be prudent to inspect the vertical head oilways.

BT

Bob,
Thanks for this alternative suggestion. However, I believe it is too late. It is good to know of this source of Hercus parts.

I guess that one of the major factors making the solution proposed by the machinist viable is the fact that I wanted to replace the front and rear roller bearings in any case. I know that there is a Timken roller bearing for the rear of the spindle that will suit the reduced spindle diameter while not compromising the load capacity of this bearing. Also the outer diameter is the same so there is no other requirement for modification of the rear bearing arrangement other than the reduction of the ID of the bearing to 40.000 mm from 41.275 mm.

Incidentally, the ID of the cone pulley was approximately 41.86 mm, not 41.68 mm as I posted yesterday. Dyslexic! So the cone pulley has worn down by about 0.6 mm or 24 thou. Given that the original spindle diameter is 41.275 mm and it is now at about 41.21 mm, there has been considerable wear on the spindle also (approx. 0.06 mm or 2.4 thou). But the problem is probably more the galling. It therefore seems that the best way to recover the spindle is to grind it down.

The machinist plans to use two bronze bushings in the cone pulley, one at either end. He says that the bushing will have superior wear qualities to the cast iron.

In summary, as you say, sleeving the pulley and improving the condition of the damaged spindle would reduce the work involved. But the end result would not be as good as getting the spindle and the pulley clearances properly sorted. Given the manhour estimate that the machinist gave me, I believe it is worth going for the optimal solution, especially given I want to replace the bearings anyway.
Regarding checking the vertical head oilways. Is there any way that you can easily remove any grease in the head and replace it with oil, without disassembly?


Greg

Hello Greg,

If you remove the bottom bearing end cap, housing the seal, you will expose to lower bearing. It should be easy enough to acertain the nature of the lubrication used. Oil finds it's way down from the upper bearing and also from the drive shaft bearings. I imagine grease would not travel far from those upper bearings. You could try to flush out grease with Kerosene.

My No. O had a Dymo label adhered to the door with the instruction, USE OIL ONLY. It was ignored.

Sounds like you have the spindle problems covered. These mills are simple and straightforward. You will enjoy using it.

Bob.

Greg
I can understand now why your mill cone pulley was making so much noise.
The wear & clearance of .024 inches was certainly a loose fit !
I just checked my mill spindle & as Bob mentioned it appeared to have an original ground finish.
The cast iron pulley bore on my mill seems to have no wear.
I would say that is because its always been lubricated with oil.
I just injected some more oil into it after reading your report & the problems associated with grease that possibly caused your problem.Your modifications should restore things.
Enjoy your Hercus Mill.
Bruce

Bruce,

This has been a real learning experience for me and it is clear that proper lubrication is so important in this area of the machine.

Bob,

I will post the photos on the forum over the next day or so.

Thanks again to you both for your help.

Greg

Does anybody know whether there are any issues with using a T belt in the Model O? I have seen some posts on the net which indicate that there are issues with these belts wearing in and requiring adjustment. However, they still seem to be failry widely used. I have a Myford ML7 and I see a large number of these machines around the world seem to have these T belts fitted. The major advantage of the T belt is that you don't have to pull the headstock apart to replace the belt.

When I start putting together the Model O after fixing the spindle problem, I have to make a decision whether to put a normal V belt or a T belt in. I would prefer not to have to disasemble things in the future to change a belt. But then again, with the amount of milling I will do in the future, a V belt would probably outlast me! Any thoughts?


Greg