9" SM Utilathe Restoration

[YotaBota]

I used 3/4 plastic water pipe for the frame and dollar store shower curtains to try and contain the chips. I didn't glue any of the connections in case I need to reconfigure.
The bench (Home Depot) itself seems fairly sturdy but the wheels are only attached to the sheet metal base and that has a lot of give. I added a heavier wood top as well to give it a bit more mass.
When I bought the machine I put a new 110v motor on it and use a link belt for the drive. The link belt is a bit noisier than a regular v-belt it won't take set if left under tension.
PeterT - Here are a couple of pics of the belt tensioner on my machine. Pushing the handle away slackens the belt (lifts the motor) for pulley changes, pulling the handle up out of the slots lets the weight of the motor tension the belt and the handle drops into the slot to hold the tension. Craig's machine had riser blocks when he acquired it and the tension handle was modified to make it work.
I don't see an issue with Craig's bench either, if the machine was a 1440 or something 6 or 7 hundred plus pounds it might be different but the lathe is less than 300 lbs.

 

[YYCHM]

Your bench looks beefy to me & guessing you have the machine mounted securely on the lugs so that should be OK.

What I was getting at is if your replacement motor is substantially heavier, then possibly its no longer a match for the stock spring if it was intended/sized for a lighter motor. Whether it fits the plate bolt pattern is kind of inconsequential. But I still don't have a clear read on the spring. Is it just meant to kind of keep some temporary tension on the belt but you are supposed to secure the motor plate down vs the spring/plate combination is 'live' and free to pivot?

Was it doing this all along & you just started noticing it? Or was it running fine up a point & now something different? Is the spring tension adjustable to see if it improves? Something has loosened up over time? A picture or more information would be helpful.

It's kind of a long story but here are the high lights.

The motor mount the machine came with relied on motor weight alone, it had no spring tensioner. It was later replaced with the tensioned version. Neither mounts have a means of lock down.

As delivered the motor pulley was pooched and had a visibly wobbled. Someone had mounted it without the key in place. That was later replaced and really improved things.

It has always vibrated to a certain extent and I always just assumed that's the nature of belt drives until I got my RF30 and marveled at how smooth it runs.

I'm just trying to figure out what's causing the vibration and motor bounce.



This is the tensioner. Loose or tight doesn't seem to make a difference.

I just aligned the motor and headstock pulleys into the same plane and that helped a little.

Craig

 

[YYCHM]

@YotaBota You have the same mount as what I started with. I have since switched to the tensioned version.

Something I've always wondered about is that my bench is tall and narrow and not all that heavy. 33" tall and 16" wide. But I can't see how that would influence the motor bounce.

 

[historicalarms]

Craig, it's not out of the realm of possibility that it is only a belt problem, usually found at the end joints. Farmers have a $hit load of "belt" experience and I "are one". The belt blemish required to produce a bounce that turns into a bearing destroying vibration at 1725 rpm can be almost un-seeable, sometimes only a slight shinny spot is all you will see on the belt sidewalls...you cant see the defect itself but the vibration can be significant.

 

[YYCHM]

Craig, it's not out of the realm of possibility that it is only a belt problem, usually found at the end joints. Farmers have a $hit load of "belt" experience and I "are one". The belt blemish required to produce a bounce that turns into a bearing destroying vibration at 1725 rpm can be almost un-seeable, sometimes only a slight shinny spot is all you will see on the belt sidewalls...you cant see the defect itself but the vibration can be significant.

Ok, I assumed a new belt would be a sure thing improvement. I'll try the original belt again and see if it changes things.

Craig

 

[YotaBota]

Craig, it's not out of the realm of possibility that it is only a belt problem, usually found at the end joints. Farmers have a $hit load of "belt" experience and I "are one". The belt blemish required to produce a bounce that turns into a bearing destroying vibration at 1725 rpm can be almost un-seeable, sometimes only a slight shinny spot is all you will see on the belt sidewalls...you cant see the defect itself but the vibration can be significant.

+1
I've been having good luck with "Continental" brand belts, the LORDCO and PA belts don't last very long and aren't cut/joined straight/flat. When laid on the table there was a visible bump at the joint in these cheaper brands, that would would cause nasty vibration.
Craig - when you go thru the pulley speeds, low to hi, does the vibration consistently ramp up or is it just in the one speed?

 

[YYCHM]

Craig - when you go thru the pulley speeds, low to hi, does the vibration consistently ramp up or is it just in the one speed?

I would say consistent between sheave positions but more pronounced in low range it that makes sense.

Man wish I had access to another machine just to compare.

I just swapped chucks to see if that had any effect. Nothing changed.

Craig

 

[Hruul]

@YotaBota , @Hruul How are your machines for vibration? What manner of bench do you have them mounted on?

Craig

I have not run mine in quite sometime. The last time I ran it I don't recall any vibration. Mine is mounted on the stand/workbench that it originally came with (looks like the one in the manual picture) which I have added weight too by storing additional chucks and other equipment inside. Also built a wooden drawer system for inside the middle.

I don't have a spring tensioner on mine, part of it is missing. I did place a short piece of pipe insulation between the motor mount and the chip pan as the motor bounces a bit and does hit the chip pan a little.

 

[YYCHM]

Swapped belts for the one @Brent H sent me. A little better but not much. So gained a little by switching belts and setting the pulleys co-planar. Neither caused a WOW improvement.



As an example of what I'm experiencing, at 900 RPM no load those chuck keys jiggle and dance around a bit. AND Ya I probably shouldn't be leaving them on top of the headstock like that

Craig

 

[YotaBota]

I just checked mine at 900rpm and 250rpm with the 3Jaw chuck in place and it's rock steady using your scientific chuck keys on the head stock technique.

 

[Johnwa]

You could apply some downward pressure on the motor and see if that makes a difference. I’m not sure it will if you’re getting the vibration unloaded.

 

[francist]

Are the set screws tight and the pulley(s) snug on the shafts? I had something like this happen once and it drove me nuts trying find it. In the end it came down to a slight bit of looseness in one of the pulley bores and while they lined up fine when stopped, under power the tension of the belt would cause the pulley to slightly cock off at a certain point in the revolution. Drove me crazy because without the belt on they were dead straight. Just a thought.

-frank

 

[Tom O]

Try it with the chuck off and is there any swarf in the spindle bore.

 

[YYCHM]

Try it with the chuck off and is there any swarf in the spindle bore.

No significant change with the chuck removed other than the noise level diminished.

A couple more observations here.

With just the motor running with no belt, there is a felt vibration in the metal table.

With the belt installed there is more vibration in high range than low range. I had confused the situation.

The vibration has a distinct harmonic to it.

The two changes made so far have improved things. Changing belts and aligning the pulleys axially.

Is something going on in the headstock maybe?

Craig

 

[YotaBota]

That motor vibration could be being amplified thru the headstock by the belt. I don't think the motor should have any vibration, is the vibration still there with the pulley removed?

 

[YYCHM]

That motor vibration could be being amplified thru the headstock by the belt. I don't think the motor should have any vibration, is the vibration still there with the pulley removed?

The motor vibration is very minor but it's there. About the same as what my mill exhibits.

I'm wondering if this table isn't amplifying things. We have metal on metal with long spindly narrow legs resting on concrete.

 

[Brent H]

How old is the motor Craig? Any bearing changes made? Many times the non drive Bearing end of the motor fails and it does not show up as a big issue until things really go south.

 

[YYCHM]

How old is the motor Craig? Any bearing changes made? Many times the non drive Bearing end of the motor fails and it does not show up as a big issue until things really go south.

Who knows, it came with the lathe. It's a made in England GRIPHON, with a big honking capacitor mounted on it. About the same physical size as the LEESON 3/4 HP on my PHS. Some one purposely obliterated the HP rating on the info plate with a punch. I doubt it's had bearing changes ever.

Craig

 

[YotaBota]

Have tried putting the headstock pulley onto the motor? The motor pulley may be out of balance.
If the pulleys fit well and are tight, here are my suggestions to eliminate the headstock.
Try these steps:
1. Is the vibration still there with the spindle in neutral? if the vibration goes away then you have a spindle issue. if the vibration is still there then that would eliminate the spindle. If it's still there -
2. remove the pulley shaft and check the bearings. if the bearings seem okay -
3. remove the pulley shaft gear and reinstall the shaft and see if the vibration is still there. If the vibration goes away then there would be a problem with the idler shaft components - bearings, gears or the shaft -
If all above checks okay and the vibration is still there then you're down to the pulleys, the pulley shaft or the motor. Bearings are cheap if yours are iffy.

 

[YYCHM]

I don't think the motor should have any vibration, is the vibration still there with the pulley removed?

Pulled the motor pulley, and got the same thing, so I don't see how switching pulleys will make a difference?

Don't get me wrong here. The vibration I feel in the table is what I'd call motor hum.

BTB - Are your pulleys the same size? My head stock pulley is larger than the motor pulley, but I guess swapped that shouldn't make a difference ratio wise.

Craig