Is there something wrong with my lathe ?

[Tim_N]

As the title suggests something feels a little off with my lathe. I have an MC900 bought 2nd (maybe 3rd) hand and I have fairly recently replaced the drive belt on it. Even more recently it feels as if it isnt spinning in a circle, more like an oval, my work, be it a pen or a bowl, feels like it is jumping in and out. I am not sure if this is something that is wrong with my lathe or if it might be just because have made a few things now and I am becoming more sensitive to it ? My 1st thought is possibly the drive wheels are a little out of shape, 2nd thought was possibly bearings, 3rd thought was perhaps the tail stock isnt quite square ?
I havent had this lathe very long and I dont really want to have to dump it and buy a new one if it might be something easily fixed (it wouldnt make the boss happy either). Anyone have any experience with this problem or perhaps a suggestion how I might get it "straightened out" ?

[OldTexan]

Tim
Check your head chuck for either lateral or vertical motion there should be none any motion will indicate a worn bearing or bushing
not sure which your lathe uses. Turn a piece of wood like making
a dowel, if it tapers toward the tail stock the tail stock is out of align
If the Main or Head Chuck like a 4 jaw or even a 3 jaw can get out of
alignment usually have to replace a 3 jaw some 4 jaw have adjustments. If you are using a center point drive, then it most likely is an error locating the center point.
I am new to posting so I hope you can understand this Texan.

[chuck1]

I would check bearings and drive shaft first and if it has a swivel headstock that it's locked in position nice and tight. Also check the chuck insert is tight on Chuck and the grub screw that locks insert in is tight

[Mobyturns]

If its happening with both pens & bowls it most likely a general alignment issue. Are you using the chuck to grip the pen mandrel too? More likely its an issue with the bearings or the reeves drive or the wrong profile belt for the reeves drive or misalignment of the spindle axis. The cast aluminium reeves drive pulleys are known to fail even on new machines - so that would be the first point to inspect. Check for cracked or broken pulleys probably not likely given you have changed the belt.

Next would be the bearings is there any apparent movement? One simple way to check is to place the chuck on the lathe spindle with a longish solid spindle of approx 40 to 50 mm diameter solidly gripped in the lathe without tail stock support. Grip the spindle on the furtherest outboard end and feel for apparent movement - could be either bearing failure or a poor mating of the chuck insert into the chuck body or onto the head stock spindle. If you slowly hand rotate the spindle using the tool rest as a reference against the outboard end of the spindle work piece without tail stock support you will be able to check any gross eccentricity.

Another possible issue could be the misalignment of the spindle relative to the lathe bed either through poor QC, damage or abuse.

You haven't mentioned what sort of chuck you are using. This could be a factor as the inserts mate/register differently for various chuck manufacturers. Also check that you are using a matched insert for your spindle thread.

Also check your tool rest - they are also known to have issues on some and have cracked and failed in some instances. If there is wear or an issue with the tool rest it could be causing the tool rest to flex giving the impression the lathe axis is "moving."

[dougturner]

Tim, this is a long shot, but you said that you recently replaced the drive belt. If the noise was not there before the belt change, this may help. I bought a new Teknatool TL 1500 a few years ago, and it was not right from the start. The people I purchased it from seemed to do every test known to the lathe, but could not fix it. I don't know which belt your lathe uses, but the TL 1500 has a flat belt with 5 or 6 "ridges" on the inside (running) surface. It is flat on the outside, but like WWW on the inside. Finally someone checked the belt, and sure nuff, there was a section of the belt where there was no WWW, and each time this passed over the pulley faces it caused awful vibration in the head stock. Most disconcerting!! New belt.... no noise.... happy woody! Check the belt first, as that seems the easiest one to start with. Hope it helps. Doug.:U

[Tim_N]

I would check bearings and drive shaft first and if it has a swivel headstock that it's locked in position nice and tight. Also check the chuck insert is tight on Chuck and the grub screw that locks insert in is tight
The lathe does have a swivel headstock, I have loosened it off and realigned it. I think that may have been a part of the problem, I quickly roughed down a couple of blanks and it seems a lot smoother. I wont know if this has fully solved the problem until I have a bit more time.


If its happening with both pens & bowls it most likely a general alignment issue. Are you using the chuck to grip the pen mandrel too? More likely its an issue with the bearings or the reeves drive or the wrong profile belt for the reeves drive or misalignment of the spindle axis. The cast aluminium reeves drive pulleys are known to fail even on new machines - so that would be the first point to inspect. Check for cracked or broken pulleys probably not likely given you have changed the belt.

Next would be the bearings is there any apparent movement? One simple way to check is to place the chuck on the lathe spindle with a longish solid spindle of approx 40 to 50 mm diameter solidly gripped in the lathe without tail stock support. Grip the spindle on the furtherest outboard end and feel for apparent movement - could be either bearing failure or a poor mating of the chuck insert into the chuck body or onto the head stock spindle. If you slowly hand rotate the spindle using the tool rest as a reference against the outboard end of the spindle work piece without tail stock support you will be able to check any gross eccentricity.
Another possible issue could be the misalignment of the spindle relative to the lathe bed either through poor QC, damage or abuse.
You haven't mentioned what sort of chuck you are using. This could be a factor as the inserts mate/register differently for various chuck manufacturers. Also check that you are using a matched insert for your spindle thread.
Also check your tool rest - they are also known to have issues on some and have cracked and failed in some instances. If there is wear or an issue with the tool rest it could be causing the tool rest to flex giving the impression the lathe axis is "moving."
I am pretty sure the pulleys are all good, I tired to see if any of the movement came while slowly turning the spindle by hand and watching the run of the belt making sure it was straight. I havent tried matching up the rotation of the chuck to the tool rest but I will do that ! I dont know what brand the chuck is but its a 100mm 4 jaw scroll chuck. I believe that the tool rest is still nice and solid, there isnt any apparent movement as long as I have it nice and tightly fixed in place.


Tim, this is a long shot, but you said that you recently replaced the drive belt. If the noise was not there before the belt change, this may help. I bought a new Teknatool TL 1500 a few years ago, and it was not right from the start. The people I purchased it from seemed to do every test known to the lathe, but could not fix it. I don't know which belt your lathe uses, but the TL 1500 has a flat belt with 5 or 6 "ridges" on the inside (running) surface. It is flat on the outside, but like WWW on the inside. Finally someone checked the belt, and sure nuff, there was a section of the belt where there was no WWW, and each time this passed over the pulley faces it caused awful vibration in the head stock. Most disconcerting!! New belt.... no noise.... happy woody! Check the belt first, as that seems the easiest one to start with. Hope it helps. Doug.:U
I took the old belt in to the shop with me and they matched it up exactly. My belt is a straight V drive belt with no WWW on it so I am pretty sure that the actual belt is not the cause of the problem.

Thanks for all the suggestions so far, very helpful. I am wondering if there is someone in the Wynnum / Manly area (or somewhere else close by) who would be willing to come and have a quick look at it with me in case there is something I am missing ? (There would probably be a carton or nice bottle in it for the successful applicant :2tsup: :D) p.s the bottle or carton would actually be full at time of hand over :wink:.

[Tim_N]

I have tried to work through the suggestions here and still cant seem to work out whats going on. There doesnt seem to be any movement with the spindle when I try to move it by hand so I am thinking its not bearings or similar. I realigned the headstock that helped but has not solved the problem.

I stand by my offer of a nice bottle or a carton for anyone who could lend a hand to help solve the problem ! Someone .... anyone ... ??

[chuck1]

What sort of stand is it on?

[Tim_N]

What sort of stand is it on?

Standard stand that a MC900 comes with. Has been bolted to hardwood to raise the level of the lathe also a wooden shelf has been bolted underneath.

[chuck1]

Maybe go around and check all bolts are tight, check the pulleys are tight on the shaft and rigid up the stand and weight it down and bolt it to floor if possible. And recheck headstock is locked in and lock nuts are adjusted to optimum position. One of my students has a similar lathe but won't be over there till next week.
When turning have you tried adjusting the speed faster or slower to see if that effects the run out?
Also check the tailstock quill lock is locking.