Member postings for Graeme Durant 1

Thanks, Bill. That confirms my suspicions! I had looked at the info on the lathes.co.uk site when I started out a few weeks back, but not since. They show a lovely picture of the underside, complete with two nuts - just as you describe. Sounds like I just need to be more brutal getting this incorrect and oversized bolt out!

Graeme

Machine now going back together, with the flanged bushes fitted nicely. All good - I did have to make and deploy a 0.5mm thick washer on the shaft, to take up a tiny bit of play between the fixed and moving bushes - but that seemed like an OK thing to do.

Latest discovery is that one of the two bolts that fixes the main casting to the base is short! And is stuck fast in the main casting. How can this be? Looking from the front, the left hand bolt is as expected and goes through both castings with plenty of length for a nut and washers. But the right hand bolt is of larger diameter, and fixed permanently into the top casting. It is just long enough to go through the base casting, with maybe one thread protruding - not enough to get a nut onto it!

When I dismantled the saw I hadn't noticed it was short - though I do recall it all coming apart slightly prematurely as I loosened the other nut, so I am guessing the second nut wasn't there. I can't see how this is right. Maybe someone has tapped or driven the right hand bolt into the casting as a bodge when the proper bolt was lost? Not exactly a workable solution as the saw swivels on its base, but you never know!

I'd really appreciate it if a Kennedy owner out there could take a quick look at their machine and just see if identical nuts and bolts are used on both left and right hand sides? If so, I will give the stuck bolt a bit more heft to get it out - and replace it with a proper sized bolt.

But it would be good to be sure what I have definitely isn't right before I go and break something!!

Graeme

Many thanks for the reassurances, Clive. I don't have much experience with these belts above one being used on my wood lathe! But it certainly seems like the way to go. Having had a look round, they seem to come in 1" increments in length, so some level of adjustment or tensioning seems important to design in. On the Kennedy, the motor is fixed but there are slotted fixings in the base where the main components are attached - so a small degree of adjustment is possible there. I guess I'll just have to by the nearest I can - as measured with string - and then work out the details once I get there!

I think however I will have to make my own pulley for the motor. At 25mm diameter on a 5/8" shaft, I have found absolutely nothing available off the shelf - not even close. At this diameter, it also doesn't offer a lot of "meat" for a grubscrew. Added to this, the motor shaft is only about 28mm long, which is broadly the width of the belt I was planning to use - the big pulley is 27.4mm wide, and so I was aiming for a 10 rib J section Poly-V belt to use all the width and get the maximum grip.

Could I get away with a narrower belt and it still grip sufficiently on both pulleys? That would help if I could.

But if not, then my best idea so far is to make a suitable 25mm diam Poly-V pulley, put one or two grub screws in the main body of the pulley, right where the V grooves are, but obviously below the level of the V grooves themselves. And then maybe cut a keyway in the pulley to add some mechanical grip, so we're not relying on the grub screws to drive the machine. The original motor shaft already includes a keyway, so a short key alongside the grubscrews would seem like a good idea. Though a lot of effort.....

Or am I overthinking this?

Thanks for your note too, Ron. I had found the plain Oilites, but really wanted to use a flanged type as it gave me the precise spacing I was looking for. As ever though, more than one way to skin a cat - and maybe a couple of 1" plain bushes back to back would have been the way to go. My flanged bushes were already on order though, so whether I made the right call will be found out soon enough!

All the best
Graeme

Thanks, chaps.

I did wonder about filling the gap with a plain bearing - in fact I could cut off some of the old bearing tube and re-use that, just to reduce the amount of space being left as an oil reservoir. I'm not sure it's necessary, but as ever there are options!

I think the issue with the "powered" saw is that the small pulley is 25mm diam, and the large pulley is around 150mm diam - a big difference, plus they are very close together. That means there is little wrap around of the belt on the motor pulley, and traction is limited. On the un-powered version, if the motor is mounted a way from the saw pulley, then there would be more wrap around, and hence more traction available. A traditional vee pulley however can't really work on the powered version as the pulleys are just too close together and the belts aren't that flexible. I think those that have gone the vee pulley route have had to use link belts to get it to bend as tightly as it needs to! But I reckon a Poly-Vee - which is thin and flexible - could be just the ticket. Best of all worlds.

Graeme

So, a bit of feedback;

Bearing Bushes - I was able to push out the scored bearing bush from the casting which includes the two hex saw slide rails. I can't completely decide if it was cast in place, but the cavity it left behind in the casting was clean and shiny, and will easily take replacement bushes - so my guess is that it wasn't cast in. The bearing that came out was a piece of bronze tube 2" long. I am going to replace this with two flanged oilite bushes (3/4" I/D, 7/8" O/D, 1/2" long, 1/16" thick flange) one pushed into each end. The 1/16" thick flange is about the same as the amount of bronze tube that was left protruding from the casting, and provides spacing against the mating components. I would have liked longer bushes, but they simply don't seem available in this size in the UK. But the loads involved I am sure will be taken up perfectly well in two 1/2" bushes. And the gap between them within the housing will act as a lovely oil reservoir! I decided not to change the two shorter bushes in the other casting, as these appear to be in better condition - almost no slop. If they prove to be an issue I can always change them later.

Saw slides - I measured across the faces of the hex sections which form the saw slides. The worst wear I could measure was a loss of 0.15mm, with 0.10mm wear more commonplace. The working faces had a bit of scoring on them, but that was all. I feel this is not going to cause me any problems, and I will just lap the faces to make them smooth again. I am assuming that if I can keep the 60 degree angles accurate, then the faces will mate correctly, under the adjustment of the fixing screws - or a spring as previously discussed. I don't see any need to mill mine certainly - some emery on a surface plate should do the trick.

Drive belt - my belt and the motor pulley were missing from the saw I acquired, so I need to address this. I was going to make a small diameter motor pulley with a crown and get a flat belt - as in the original. I know however that these can be prone to slippage. Then I found an interesting video on Youtube showing how an enterprising chap and used a Poly-V belt to address this slippage on his Kennedy saw. He made a parallel motor pulley with the appropriate multiple vee grooves, deployed a Poly-Vee belt, but ran that on the original crowned big pulley. His belt was as wide as the crowned pulley could accommodate. I guess the small motor pulley is where the slipping occurs, it being only about 25mm in diameter, and close to the big pulley - so little wrap around of the belt. Slippage on the large pulley is likely not an issue. So, my plan is to replicate this setup. All I need is to grind an HSS lathe tool appropriately for the vee shape of the Poly-Vee belt!

Drive Belt Cover - mine is missing. I don't suppose anyone out there has an old spare one lying around....?

Any thoughts or comments are very welcome!

Graeme

Seems like I started a list of woes here by asking about the worn bushes! My slides looked reasonably OK - a bit scored, and with small burrs on the corners of the hex at a couple of points - but not obviously worn. I was planning on filing the burrs and just cleaning up the faces. That said I think I now need to measure their "across face" dimensions and see how that stacks up. I'm away right now but I'll have a look when I'm back. Maybe I'll have the same problem myself!

I don't suppose the hex bars are hardened in any way - case hardened maybe? Otherwise they would surely wear pretty quickly, especially since similar hardness materials acting as bearing surfaces are not generally recommended. Just a thought.

Until i look at my own slides however, it doesn't sound like anyone so far has tried to change the bushes. I thought I'd try making up a small press-piece on the lathe that fits the I/D of the bush with a step slightly less then the bush wall thickness, and see if it can shift them with a bit of vice pressure. That at least will tell me if I need to bore or ream them out.

Graeme

I'm in the process of rebuilding a very scruffy Kennedy powered hacksaw, and find that the main shaft bearings are very worn - especially the long main one attached to the base.

The bearings are plain - and nothing fancy, in fact they look more like copper tube. I'd like to change them, probably for Oilites. Has anyone replaced them, and if so, were they just pushed in? They look well seated, and so I'm just hoping they are replaceable and not somehow cast into the alloy, like some of the other fitments on the saw!

Any experiences or guidance would be most welcome before I just have a go!

All the best
Graeme