Member postings for Simon Williams 3

Could you add dimensions to your description, not least to ascertain if this could be made the old fashioned way. That would let me ( and maybe others) do some calcs about how to go about making said gear.

Sticking this in with the 3D printing stuff suggests that you're maybe expecting this to be made that way, rather than cut out of metal. What materials does this poorly gear run against, and is there a reason why a gear cut in metal would be unsuitable?

Rgds Simon

I had one of these a while ago I bought out of curiosity to try plasma cutting. I thought it was the vicar's underwear until it got nicked. I bought a much fancier replacement so I could weld alluminium. and a dedicated plasma cutter, but for the money I think this is a brilliant idea for a Christmas present. Enjoy! Simon

Andrew - whereabouts are you? I'm in West Gloucestershire and there is a slotter in my shed. Alternatively if you bore them and post them to me I'll slot the keyway and post them back Best Pm me if you're interested rgds Simon

I looked in the cupboard, but we were fresh out of baked beans....

Seriously, I guess you spotted my home made "crucible", made out of a few bits of 5 mm thick m/s plate. Yes, it's a bit overkill, but that's what I had in stock. It was also ready cut up (nearly) to size, which is why it's the size it is, and a quick zip round wiith the MIG and I've got a pot I trust to stay solid while heated to 400 degC or so. I managed to stop myself wasting another evening making a pair of crucible tongs!

It's better fun than watching evening TV

Thanks for your interest

Simon

Edited By Simon Williams 3 on 25/11/2016 19:19:38

Here's a picture of the lead casting cooling - this is the second one.

And here's a picture of the finished article

Was it worth all that commotion - never in a million years. But I enjoyed it!

Well, I liked John Olsen's suggestion of casting a lead insert in situ, rather than the complicated plan I'd thought of to machine the socket out to avoid stretching the casting. So Here's a picture of the state of the poor old hammer, which prompted my initial post

The tatty hide end came out by following the instructions from Thor - drill a hole in it and unwind the leather. Easy Peasy. I resorted to amateur dentistry to extract the copper insert. If I'd realised what thickness of copper still covered the cast iron I wouldn't have bothered.

Hey Thanks Nicholas, I've downloaded the info from Thor as per your link, now I KNOW it's a lost cause.

But the other thing that comes out of this is that the instructions from Thor say make the "combination tool" from BDMS then harden to 58 - 60 Rockwell C. B****dy funny mild steel!

I have another cunning plan, which I'll have a play with over the next few days. If it's worthy of notice I'll upload the results.

Again, thanks for responding

Simon

Well, Crikey! Talk about chapter and verse!

So the situation runs something like this. I can buy the new inserts for about 6 to 8 quid a kick, then I need a 50 tonne press and some fancy tooling to mend my hammer I've had for (conservatively) 40 years and that owes me absolutely nothing. I'm a believer in tradition, but this is a no brainer!

Dare I admit that I've already bought a replacement (for 13 quid plus postage) at this point?

But damned if I wouldn't have a go, with my home made 50 tonne press, just to see if I can!!! I bought the inserts about 30 years ago, never got round to it (not done it yet).

I'll take a photo before and after and see if it works out. If it's not too shabby I'll let you see them!

Heigh ho! Thanks guys for responding.

Simon

Hi all,

Does anyone know the magic spell for getting the leather insert out of a Thor hammer and then getting the new one to go in (and stay in) the hole? Is it just done with brute force, or is there something more scientific involved?

Does the same abra-cadabra work for a copper insert?

Best rgds to all

Simon

Don't know if it helps, but here's a picture of the cross slide on my Bantam (Mk2) which has various holes in it but not the one you've picked out.

Indication might be that the hole in question is an aftermarket feature?

HTH Simon

Edited By Simon Williams 3 on 11/11/2016 22:19:20

Does anyone have any details of the internals of the type 2 vertical head for a Centec milling machine - that's the one without the quill feed?

I've just bought one, but have realised that the driven bevel gear on the vertical spindle floats up and down on its keyway. It doesn't have anything to locate it lengthways (vertically), so there is nothing except gravity to resist the separation force of the two bevel gears running together. I'd expect there to be some sort of location collar?

I don't want to run it and discover that I've stripped the teeth!

Thanks as ever in anticipation of some help!

Best rgds Simon

So the interesting debate for me is, having agonised over modifying the internals of such a well designed machine, I've eventually decided to alter its design. In the eyes of many I'm sure this is heresy, and repairs should be carried out with as close attention to keeping it original as possible.

Comments anyone?

A matching keyway in the cone pulley, throw it back together, nice and true BUT IT STILL KNOCKS!!!!!

Stripped the motor again, to find a very small mark on the outer of the rotor, and a corresponding excresence of something hard and nasty that doesn't belong in the stator slots. Clean it out, all back together and runs as sweet as a nut.

But this didn't solve the nasty knock in the drive. So I decided (with a deferential nod to John Stevenson) to repair the drive end of the motor spindle as the pulley was running about 20 thou' out of true, thanks to the damage of the grub screw coming loose and chewing the end of the shaft. The picture of the damage to the motor shaft is out of focus, so just imagine a 14 mm dia stub with a 5 mm keyway, chewed by a dog point grubscrew which was the location, fastener and drive key. Cheap and cheerful until it came loose! So here's the repaired and lengthened motor drive shaft, with a blind key way cut in it.

Here's the top casting with the rollers in place, and the inner spindle ready to instal. The PTFE washer is a thrust bearing just to separate the alloy drive pulley from contacting the alloy housing, as the needle rollers have no axial location.

So I decided to go for needle roller bearings, as there was not enough meat in the casting to accommodate ball races. I toyed with making like for like replacements, but using needle roller bearings was actually easier as it meant I could keep the worn inner, and not have to remake this bit with its captive key.

So onto a faceplate with the top casting, and bore the bearing recess to 1.624ins to take two standard needle rollers. There was room for a 0.250 thick spacer between the two bearings. I liked the idea of two bearings, as the pulley runs above the bearings as a cantilever. The change wheels are there as a token counterbalance.

Having watched Damian Noble's thread re-building his newly acquired Tom Senior mill, I have been spurred into action to tackle a project I've been ignoring for several years. The pulley driving the quill is supported by a plain bronze bush, and the steel inner drive piece has worn where it runs in this bush. I had diagnosed this as the cause of an annoying rattle/knock coming from the head - but more of this later! The bush inner diameter was scored, but still true to size, but the steel was worn as shown below.

Hello again, could someone who knows about the innards of single phase centrifugal start motors comment on this for a hypothesis please?

If the start and run windings were correctly connected in reverse, but somehow swapped in forwards, would this explain what we're seeing?

Rgds Simon

Hi Paul,

Well, I was totally confident that the nameplate would show the motor was half horse power or thereabouts, and we could put this to bed. Shows how much I know! 2 HP should be plenty.

However, there are a couple of questions that arise out of the information you have posted, as I fancy the original motor would have run at 1450 rpm, and this motor runs at twice that speed. Do you have a means of measuring the ACTUAL speed at the chuck, not just what the gear lever nameplate says? I just wonder if the whole thing is running at twice the speed indicated, unless whoever did the conversion did the right thing and altered the pulley sizes appropriately. If we're actually running at 1600 rpm then 2HP on a single phase motor might well be marginal. I can't gauge the speed from the video.

My second question is just to confirm the full load current as indicated on the motor name plate, just to check that it correlates with that of a 2HP 230 volt single phase motor. If you can get a piccy of the nameplate so much the better.

Failing that my next best theory is that there is something odd with the motor run winding, though I can't fit that with the proper operation at lower speed at the moment.

Mmm. Interesting. The thick plottens.

Rgds Simon

Motor is underpowered. With the start winding energised it has enough torque to accelerate the machine from standstill, but then the centrifugal switch opens (at about 70% full speed or thereabouts) and the motor now hasn't got enough torque to continue accelerating the gear train etc up to full speed. So the motor begins to stall, and slows until the start winding is energised again by the centrifugal switch where it begins to accelerate.

Solution is a bigger motor, or don't use the 800 rpm range. Maybe this isn't the original motor - someone maybe converted it from three phase but fitted an undersized motor?

As Neil says, it's just a quirk of the internal geometry of the motor that it will develop enough torque to run to full speed in reverse but not forward. Single phase motors are like that. The gearbox sounds fine, I wouldn't go investigating the bearings, that's just a can of worms which is probably irrelevant for the time being.

We'd still like to know what the motor rating plate says is the rated power of the motor. I've got a Bantam 2 with a 1.0 HP motor, that's not got enough oomph to run at 2000 rpm but otherwise it's fine.

Measuring the supply current on a single phase motor isn't going to resolve anything, you would need to measure power factor as well, as the current stays very nearly constant as the motor is loaded, it's the power factor that changes in response to the shaft load. Also the supply current changes drastically as the start winding cuts on and off so measuring the supply current under running conditions is far from straightforward.

Lovely machine - lots of good work here even if the top speed is outside its capabilities for the time being,

HTH Simon