Harmonic Vibration At 1000rpm

Quick update, I have ordered a set of needle rollers these have an inner and outer race, will need to machine both the shaft and the housing for them to fit.

Hopefully a cheaper option to repairing the shaft and housing to still being only able to fit a bronze bush back in. Still not sure if it was built with brass bushes or this is a previous repair.

What are peoples thoughts on cleaning out the headstock ? I was going to drain and flush with shellite and refill, just worried about contamination in those Gamet bearings. I could see a small amount of brass material in the little feed cup arrangement that feeds the front spindle bearing, Not enough to cause damage Id think, but still don't want to go through this and then have those fail.
 
Hi Kiwi,

No i haven't done anything yet, not sure what you are suggesting? Buy a new input shaft assembly from them, sell my lathe to them, send mine to them to repair?
 
Sorry had to dash away. I was suggesting that perhaps they may have the right bearings that you are after sometimes it's better to spend a bit more and get the proper parts than to re machine for an alternative Colchester parts are expensive and hard to find Nobilla's has probably the largest range of the older round head colchester parts that I have found and I would put it to you they won't be around much longer and also freight costs will be the killer as there nothing light in colchester
 
Well an update, I emailed Nobilla and they were very helpful. at the time they had one shaft but it turned out to have different number of teeth on it to mine, also with the Aussie dollar some where far below the toilet region it was also extremely expensive.

So I bit the bullet and machined the shaft and housing to accept larger needle roller bearings. It turns out the shaft wasn't even hardened? it turned down very easily, in light of this I'm glad I went the way I did, I had to speedy sleeve it for the seal too as I think it would wear in short order. I have got the lathe up and going again and it runs smooth as silk, very happy.

I am still not impressed with the belts, I have got three "matchless" Gates power II belts. A84 but they are just inconsistent, one even causes a light thump as it travels over the pulleys!

So I am looking for options, I have found a 3 ribbed Gates belt powerband back, so its three joined together but I cant get them over here and cant find a seller in the States that ships over here, so what other belt options do people use?

Ideally a single belt with 3 ribs would be the best I think, anyone on here sell belts?

Cheers
 
What about a cam timing belt means changing the pulleys
 
If i hadnt just bought 3 more belts i would seriously consider it, the new gates ones i bought are no good. I ran it for half a day and it was fine at 700rpm. The motor got hotter it would vibrate at 1000rpm. It shakes the machine slightly and it has a slight knocking noise in the motor. Im over it. I bought a new motor and am going to put it in. The irony is it will probably have a different shaft size so i will need a new pulley! Did i mention im over it.
 
If only! Im on nightshift so I was playing before work, although a few stubbies before would make the night go easy!
I fitted the 3 new carlisle belts I ordered and they are much better, I also scored a belt pulley laser aligning tool off ebay so I will double check everything is good when I finish work this week.
A new teco monarch 5hp motor is on its way, thanks ebay again, also decided to fit a vfd next week off too, after I make sure the vibration gone, one lot of problems at a time!
 
Well I skipped ahead and put the VFD on to the lathe before changing the motor..... and it works awesome!

I have tested it and with the lathe in top gear I can start off at about 40hz no vibration, as I creep up to 50hz the vibration starts to develop getting worse until the hz gets to roughly 55hz then it comes good? at 60hz even to 70 it runs smooth as a dream!

After some reading up apparently there is a thing called 1 X rpm vibration where when the motor is running at a very close speed to the driven load it can cause a harmonic vibration, solution is to change the gearing or the motor as often the motor has unbalance or something at its rated load speed. Weird anyway.

So once I machine a bracket to suit the flange face on the new motor I will put it on and hopefully all issues will disappear. Very impressed with how smooth it can run with vfd, need to make a bracket for a speed pick up on spindle and then I will be able to pick rpm with the dial and gear changes! Flasher than a rat with a gold tooth!

Cheers
 
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