belt conversion for Sealey Mill sm2502

I took delivery of a belt conversion kit from Amadeal, realising that I would need to do some 'adjustment' to make it fit properly. The pulley bores are wrong but that's not a problem, however, the fixing hole positions in the two plates are not quite right either. Also, it strikes me that the length of the standard motor shaft is just right for the original gear but there is a lot of overhang for the belt pulley and nothing to support it. I could foresee problems with the shaft chewing the alloy pulley bore.

I'd be interested whether anyone has been down this road and how they have found it. It's a case of a bird in the hand etc. but it might have to be a temporary solution. I have to do something because the big gear on the spindle developed a crack and chewed itself up. It had the habit of producing a frightening slapping noise at times after working hard and I think that's been the final result. Replacing it will involve more dismantling as it seems necessary to take it out via the back of the box. (?)

People say that there's a kit from little machine shop. Has anyone tried that? I could certainly do with having a quieter workshop.

I'm sure that some of you will say I should just make one . . . . .

Cheers

Andrew Lyner

A Google search for your mill threw up several pictures of a mill that I recognised as a clone of one I once owned. This is going to test my memory somewhat. Way back in late 2012, I had an Amadeal XJ-12 Mill that suffered from noisy and exploding nylon gears. Internet searches lead me to The Little Machine Shop in the USA, from where I ordered their belt drive conversion kit. In my haste, I failed to read the warning regarding the bore size of the spindle pulley. Of course, mine was 28mm and the supplied pulley was 30mmØ. No matter, I thought, I'll make one on the lathe. I did and it fitted. The hole spacing for the mounting plate were at a slightly different pitch on my mill as well. It was turning out to be an expensive purchase, with few parts that were a direct fit Undeterred, I went ahead with the mods and ended up with a working example. The only surviving photo is this one:

I also stripped the gear head and removed the stock two-speed gears and shaft, further reducing the noise. This involves the removal of the head from the mill - awkward but not difficult.

I have a pdf file of a scratch built conversion with full drawings (in Imperial units) and a couple more photos of it which I'll email to you if you would like it. Just PM me with your email address.

Just had a look in the workshop and I still have the original unused spindle pulley with 30mm diameter through hole and its associated belt. You are welcome to these, if it will help your project along.

John

Thanks for the offer but I have all the parts. But some drawings could be handy. I'll PM.

That looks like the present little machine shop version. I have the parts of the amadeal one and, from the blurb on las site, it's still not compatible so, in the absence of a Sealy Special, I think I'll modify the plates with different fixing holes. Scheme I don't have a working mill or I could fill the existing holes with weld and drill four more, in the right places. But I have a work around in mind and there's plenty of room up there for another thickness of steel for fat washers.

Question for you: how long was the motor shaft on your conversion? Did it go far into the pulley?

Andrew,

I have your pm and will respond soon with the pdf file. Sorry, I can't remember details about the motor shaft length etc.

John

John

No worries about the shaft length. I think I need to get things into (engineering) perspective. Those massive bearings on the spindle need to handle some serious forces but the motor shaft is pretty much decoupled from the cutting tool and those forces. I will need to fit the new 10mm pulley onto a 9mm shaft and I can open the pulley bore a bit and use a long steel sleeve to protect the soft alloy bore.

All the rest of the 'fitting' is normal bodgery. The plates are nice and substantial on the amadeal kit, Black steel and not the shiny stuff on the lms version but well beefy enough for 1/2hp motor.

No rush on the pdf; I'm tied up on other things for a few days - I was messing about with home lighting fittings. They are seriously sub standard, even on very expensive (John Lewis) ceiling lamps.

Andrew

A friend encountered a similar too short motor shaft issue on something completely different that also had a vertical mounted motor with a good deal of the motor shaft length used up by the mounting.

After due discussion we decided to make a stepped extension shaft having a decent length of bore to securely hold the motor shaft followed by about 1/2" of solid before the thinner extension sized to fit the pulley bore. Suitable spacers lifted the motor to achieve belt alignment.

Worked out OK but great care was needed to get the extension made concentric to the motor shaft and the motor raised squarely.

Looking at Johns photo the design looks seriously over chunky. There would seem to be considerable scope for dropping the motor lower if a flanged weldment with thinner base were used to hold the motor. I've made that sort of thing work in the past when my welding skills and equipment were much more rudimentary than they are now so it's not stupidly difficult. No working milling machine then either.

Clive

Clive,

Your perception of the chunkiness of the plates might be skewed by the scale. If I remember correctly (always a rash assumption) the base plate was 12mm thick and the motor mount 10mm. As they came from the USA, more likely Imperial equivalents. As an aside, the plates in the pdf to which I referred (also of USA origin) were 5/8ths and 3/8ths respectively. This is the photo of that installation lifted from the pdf.

Sizes are selected to facilitate the alignment of the belt, I suspect. Chunky or not, it worked OK. And I'm quite a fan of "chunky" over "wobbly"!

John

John

Entirely agree with the advantages of chunky over wobbly.

The welded up from sheet flanged motor support plate I was specifically thinking about when making the previous post was made from 12 gauge or, possibly, 2 mm sheet steel. It firmly held a 2 hp 3 phase face mount motor in position. Probably a plate would have needed to be something like 3/4" or 20 mm thick to be equivalent rigid. Which just wasn't going to work for belt alignment reasons.

Scrambling for every fraction of an inch or mm to get belt clearance. Maybe 1/16 inch / 1.5 mm or so clearance between belt and plate in the end.

So it all worked out.

Or would have done if I hadn't hated the result and binned the whole idea. The aesthetics were terrible and, although it all technically worked well I couldn't live with it. Fixing what I wanted to fix rolled in a whole lot of unexpected compromises in other places.

Clive

Just to tie this up: The belt drive now2 works. I had to modify pretty well everything;

All eight hole spacings in the plates were wrong, the spindle diameter was a tad too big (easy to sort that out) but the pulley needed shortening to get the top nut on the spindle. The motor shaft is pretty short and undersized but I made up a steel sleeve with a key sized slot and a a hole on the other side for the grub screw. Then the stub needed shortening to get the belt lined up but the pulley seems pretty firm on the shaft with no rattling.

After all that fiddling and cussing, there was silence . . . . . just the sound of the cutting tool on the fly cutter, tearing through aluminium. No slapping, jangling or graunching noises and the tool just stopped when overloaded, leaving no nasty groove. Just like the book describes. I can't help feeling that the spindle had been jumping up and down a small amount, generating all those previous noises.

One day I'll make two plates with the right hole spacings and even be bothered to paint the danged thing. Thanks for the positive and useful comments chaps.

I have to ask why the original design didn't use a belt and pulleys. Bench drills all use them.

Andrew

Edited By andrew lyner on 04/05/2023 21:49:58