motor’s running but the belt’s not turning

I got my motor running on my C&P 12x18, it’s a star-kimble 110v variable speed motor.

Right now I’ve got the rollers off and I think I’ve oiled it up pretty well to reduce any dragging, but I still can’t get the motor shaft to turn the belt. It either just hums and doesn’t spin, or it spins too quickly without turning the belt.

The belt is leather, kind of old, and slips off when the motor does get it to spin for a second. Could it be that the belt needs an adjustment, that it’s too loose? The motor shaft is kind of jerry-rigged with duct tape, seemingly to thicken it up and keep the belt on. At most it stays on/spins without slowing to a stop for 2 impressions. I’ve read on here that, oiled well, I should get up to 4 impressions, right? Should I be using more oil? I’ve got 30w motor oil and WD40 in there already, but I’m sure I’ve missed a few oil spots.

Any suggestions/tips?

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Are you spinning the flywheel by hand to help get the press started?

Tension and alignment are often fiddly… an older belt may have stretched or distorted making exacerbating the issue.

Are you spinning the flywheel by hand to help get the press started?

Tension and alignment are often fiddly… an older belt may have stretched or distorted making exacerbating the issue.

OK, bunch of questions coming. By working thru them, we should be able to get your press up to speed and ink on paper.

The part that sticks out for me is the duct tape on the motor shaft. What shape is it in?, sticky, oily, frayed, etc?

Is the belt dry on the inside surface? Even a little oil can cause problems if the alignment is not right.

How tight is the belt? Either too much or not enough tension can cause problems with runoff.

Can you describe the way the motor is mounted? If it is loose, then it could be shifting enough when starting to throw the belt.

Did this happen all of a sudden, or is it a problem that is getting worse? Or did you just install the motor?

Can you post pictures and or video?

While there are “belt dressing” products on the market that would probably help short term, I prefer to find and fix the root problem/s and have a machine that is reliable.

From the comfort of my armchair quarterback viewpoint, I am going to guess that there is probably one big issue and several small issues that have joined forces to cause your problem.


thanks for the quick responses!

@anonymouse, I am spinning the flywheel! a good hard shove and then continuing to push as the motor kicks in

@marshall: the duct tape isn’t sticky or oily, just old and frayed. parts of it have worn down to the string netting under the tape on the top layer

the belt is dry, but it’s not very tight. it takes a little coaxing to get on when it falls off, but not enough to be considered tight I don’t think.

the motor is mounted off the ground on a few beams attached to the back of the press. it’s definitely loose—I think this is probably my issue. when I try to change the speed on the motor, pulling the speed control shifts the whole motor an inch at least.

this is my first time running this press!
I’ll attach photos below. sorry they’re so low quality, I couldn’t get them to upload otherwise!

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need a pic of your speed control system I may have a solution

2 or 3 (possibly or possibly not) helpful points:-
Assuming the motor is mounted even reasonably square and solid. up and down movement, initially, not critical, remove all the Duct tape, examine the pulley, checking to see if it is completely flat across the working surface.????
The reason being (generally) with No Jockey pulley or Belt guide of any kind, Either the flywheel, OR the Pulley has to be CONVEX to keep the belt running ON.
On initial startup, it is quite normal for the belt to attempt to throw slightly sideways, 50/50 either *off* or into contact with the end bearing casing.!!
One tiny experiment, to check for warp on the overall length, take it off, replace temporarily, backwards to see if it wanders further *IN* implying *shot to bits* and Replace if possible of course.

Whilst the belt is off and with the Duct tape removed also, with either LONG engineers straight edge, Or 100% accurate hardwood strip of Timber, Or Braided fishing line offered up across the end face of the Pulley and across the outer face of the Flywheel, (taking into account that the driving pulley may need an accurate spacer 2 em, 3 em, etc to achieve true parallel from the driving pulley.

NAKED EYE usually will not show out of Parallel,

Straight edge, Plumb line, etc. is a good starting point.!!

Check to see if there is any means, on the base of the motor, for adjustment(s) backwards and forwards for initial belt tension, and the ability to *skew* the Motor for the alignment as above.

Re your initial comments about the reluctance of the motor to fire up, with the belt off, just a simple test (motor not running) test/detect movement in the bearing immediately behind the driving pulley, NOT laterally, rather up and down, the reason being that (that) bearing usually takes a beating, and even .002” movement allows the Armature/Commutator to come too close to the Stator or Casing, causing Your *Humming & Not spinning* possibly.? Just a chance.

Re the absence of Convex Driving pulley and/or NO belt guide, it has been well documented on B.P. recently that Convex Pulley,s of the correct circumference and shaft bore size are obtainable from your Factors/Suppliers. Good Luck Mick..

Addendum, re your second shot, could be angle of view, strange fray of the tape, or possibly?? crude attempt from previous owner, by building up the Outer edge of the pulley with tape to make the belt run ON.

Not an easy concept to appreciate, but completely counter productive, the belt just ramps up and Off rather than being persuaded *ON* hence Convex.

Thanks for the answers, now some more questions, grin!

When you put the belt on, do you loosen the motor and then re-tighten or just fudge the belt on however you can?

With no power on and press stopped take the palm of your hand and press down on the belt about midway between the motor and flywheel. How much can you depress the belt?I know this is tricky due to the fact that different people can apply widely varying amounts of pressure. Does the motor move or shift when you do this?

How wide is the belt and the motor pulley? If the motor is not moving around when you press on the belt here is a trick to help eliminate some possible issues. My guess right now is the motor movement is causing the bulk of your issues.
The trick is to take a strip of duct tape about half the width of the pulley and wrap it around the center of the pulley 2 to 3 times. This will give the pulley some crown and will help to center the belt when it runs. Not a long term fix, more of a troubleshooting guide.

If crowning the pulley helps then it is time for a new pulley. Either wood or cast iron pulleys would work, I can offer suggestions on where to order one later if you need.

First steps I would take if the press was in my shop would be to verify how much the motor moves and get that issue solved, and while doing that put in place a way to adjust the belt tension. Then I would check the alignment of the flywheel to the motor and finally replace the pulley if needed.


another option could be to replace the pulley for a vbelt pulley with the corresponding vbelt

Thanks Mick, will look into those things! I definitely think the duct tape was an attempt by the previous owner to do just that, haha. They were using this press rarely, just for die cutting.

I was just fudging it, but I’ve figured out how to move the motor back and forth now, so I’ve been doing that. With tension, even with pretty light pressure, pushing down on the belt gives at least a half inch, maybe more. and the motor’s pushed back about as far as I can get it.

The belt is 2” wide. The motor isn’t moving anymore—It was before I tightened it up and moved it back. I’m still only getting one impression and not enough momentum is going to pull the rollers back down over the chase.

Could you send me the resource for pulleys? I’m going to try crowning it and see what happens. If that doesn’t help I’ll take all the tape off and take a look at the condition of the pulley.

you could also try to clean the pulley with gasoline and apply some to the belt this will add friction

The first place I would try is

The next link shows the different styles they make.

The fixed bore towards the bottom of the page would probably work best for your press. No need to get into higher dollar bushing style pulleys.

WW Grainger and McMaster-Carr are also 2 places that stock cast iron pulleys.

My personal preference for small pulleys is wood and/or paper. They grip better on older belts.

Worse case you can get a cast iron pulley with flanges. We should be able to get the press to run without going to that extreme, hopefully.

My suggestion is to try taping the pulley, and then if that doesn’t help try a little bit of spray belt dressing. It won’t take much to give some stick to both pulleys and the belt. Too much can cause long term issues that take time to recover from. Walmart has cans in their auto department.

Another idea is to have an flanged idler pulley installed on some new fabricated mounting brackets. This would take care of several issues, ie; would help keep tension on belt, make it easier to change the belt, help keep belt on motor pulley and increase the wrap angle on the motor pulley. Wrap angle is how much belt is in contact with the pulley.

Keep us informed of what works and what doesn’t and we will do our best to help out.


McMaster also has some nice paper pulleys. They are crowned in the center to help to keep the belt from wandering.


Thanks so much guys. I’ve got it to where it will run consistently now—but only at a “sweet spot” of speed that’s a lot slower than where I want to be. If i crank it to a higher speed, I get the “humming but not turning” problem, like there’s too much drag to get the belt turning. Is that something a new pulley or belt dressing will fix, or does it sound like a belt tension/motor position issue?

I moved the motor slightly to the left after doing the fishing line test and it has helped get it to where the belt doesn’t throw off and it keeps going. I’ve still got the pulley taped up pretty severely for now, until I can get a new one delivered to me

Still a little concerned re the *Humming etc*
Ideally have a tame friendly Sparks! Electrician do a continuity test, as before, that scenario can be indicative of Shot bearing, but still possible to get percentage of motive power UNTIL more load is called for, Or one internal winding is on the way out, eventually (expensive) failure. Or there is a phase missing or intermittent which will cause Humming, Hunting, (searching for power) ask your friendly sparks to clarify, possibly.
Again (check with sparks if poss.) *Humming* and lack of power can be a sign of faulty Capacitor, = small cylinder,? with 2 wires, not necessarily on the motor, possibly found on the variable speed equipment, will allow run, but power loss, possibly irrelevant in U.S. If so, Apologies.

Here in U.K. with our conventional 3 phase, it is quite possible but only happens infrequently, IF one of the 3 phases, incoming, develops a fault, the Motor will run at reduced power, especially if the starting solenoid is on one of the 2 good phases, the safety devices R.C.B.s (residual circuit breakers) knock out eventually, but not an ideal situation.

Understandably KEEN to *Get the Press,s Rolling,* but as the saying goes >Make haste slowly< it will be cheaper in the end.

Your efforts, findings and results will be appreciated by those following on behind. Again good luck.


As the Wife of the Main Man in the film *THE ABYSS* says, (and hopefully you will be able to say the same) >>*LUCK IS NOT A FACTOR*<< Fantastic quote and put down.

I agree with Mick, the “humming” is quickly becoming the newest issue to deal with.

Is the motor making the noise or is the belt slipping on the pulley and creating some background music?

You will be very lucky to find an electrician that has any knowledge of the style of motor used on this press. Their method of speed control is different from anything built in the last 60 years and most sparks have never seen or heard of anything like it.

That said if you can find someone that is “GOOD” at troubleshooting it would be worth an hour of service charge to have them come out and check simple things like voltages, amp draw. Another test that can be run is with a “megger”, this checks for possible problems with the insulation of all the entire windings.

Hope this helps


How about a picture of the plate on the motor? Could it be that the motor is a dual voltage motor and that it is currently configured for 220 but is plugged into 110?

The variable speed Star Kimble motor that I had on a 10x15 a while back was definitely dual voltage.


Here’s a picture of the plate. I really hope it’s something that simple! I’ve already called a few electricians locally before (my landlord accidentally flipped my breaker and I didn’t realize because it was just the one my press is on and not my lights/fans/other electric, haha) and no one I called felt like they would be able to help me.

And honestly I’m not sure I even know how to fiddle with the speed control correctly, it seems like turning one way pushes the flywheel counter clockwise and the other way goes clockwise, but I can only really find a sweet spot on the counterclockwise side. Plus I put the rollers back on and I can’t get more than one impression anymore—getting off the inkplate and onto the chase & vice versa seem to be too much.

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I should clarify on the humming—it’s the sound of the motor being on, very slight noise. it’s not whining or putting out a loud him. it’s just that the motor seems to be running without being able to turn the flywheel, even with a shove-off from me.

This is indeed a dual voltage motor. There should be an access hatch on the motor with terminals. Typically there is also a diagram on that hatch that shows how to set them for 115 or 230.

This may be just what you need-

image: Most specifically, this.

Most specifically, this.

Hopefully Daniel, (D.G.M. @ the Arm.) has given you a good extra pointer to figure out if it be wired 110 or 240.?

One more possibility, that your shot of the specification plate has thrown up, the plate states ONLY 1/3 Horse Power (One Third H.P.)?
If you trawl Google etc., which includes references to Briar Press, 1/2 H.P. appears to be the MINIMUM power capacity required for this size Press.

If the Pulley has been increased in size (with duct tape) to gain a little more M/c. speed coupled with (albeit small) but under powered Motor, it could be the proverbial *Straw that broke the Camels back* . . With all the other factors being 100% and in an ideal world 1/3 H.P. MAY have sufficed.

I quote an example from long association with, specifically, Monotype, Casting Machines, i.e. even with 3 phase supply available,working through variable speed controller, 1 H.P. (One H.P.) was the MINIMUM capacity we could hope to run with.

Eventually and via Mechanical variable speed gearboxes and still to this day (with the few still operational) 1/2 (Half H.P.) running from 3 phase works perfectly.

One tiny exception being, (the equivalent of your press stalling where the Ink Roller train climbs the ramp,s and compress,s the return springs) where the Caster stops in mid Cast with a fault and the Lead Pump is in circuit, with all the will in the world, 1/2 H.P. struggles, and has to have a little extra help.!

Think in terms of your M/c. rolling over heavy impression, (which seems to be the norm, in this day and age) with the poor little under powered motor giving its best in an unequal battle.

In theory the weight of the Flywheel and Momentum Should carry it over impression, etc,etc… Good Luck.

Thank you Daniel! I’m looking at the motor and have no idea how to rewire it, but I do believe that it’s set up for 230 or is at least not set up correctly for 115.

I’m asking a local motor expert for some help with this one but I’ll keep you guys updated once he’s able to come out and take a look at things for me

The motor was wired for 220! Had an electrician come down and spend about 20 minutes with the press and she’s rocking and rolling. Thank you everyone for your help!

That’s what I thought! I am glad you are back in action.