Member postings for Pete Rimmer

Rich,

I have done exactly that thing. It's no trivial exercise but it does work to yield a 240V delta-wound motor. How successful it will be in operation is unknown for me I do know that the motor runs on a VFD but tends to whistle a bit.

Pete

Looking again at your resistance figures your motor IS a Dahlander connection one. Typically you would have six wires out to the pole changer switch and the three that will form the star point and 3 that are in the middle of the straights will have approx. 2x the resistance of the other combinations.

Here is a typical 2-speed reversing pole changer arrangement. In low speed the power is sent to the three corners of the triangle, in high speed the corners are connected together and power is sent to the nodes in the middle of each straight side.

In the image above if you count the contactors 1-7 from top down:

1,2 and 7 switch in high speed (1 and 2 providing phase reversing)

3,4 and 6 switch in low speed  (3 and 4 providing phase reversing)

5 creates the star point, when high speed is selected in either direction.

Edited By Pete Rimmer on 15/02/2023 21:23:15

Edited By Pete Rimmer on 15/02/2023 21:33:27

Usually the star point is easy to find because it is tied on top of the windings after the motor is wound and then tested. The winder will leave all of the winding ends accessible, test them individually, then connect, insulate and tie them in to the winding before laquering/encapsulating so that they don't move and rub through the insulation. The star point will usually be and obvious junction of 3 winding ends if it is not fully taped over or appear as a large bulge if it is.

I had a 2-speed Newman motor which had two entirely separate windings for low and high speed, so it may well be a Dahlander connected motor but eqully it may not.

Rich: Have a look on the inside of the motor terminals cover there should be a connection diagram.

Edited By Pete Rimmer on 15/02/2023 20:22:54

What wattage is that James? If it's 65W then I could spare one of mine for you as a replacement. I have a 125W (110v) , had a 100W but it got destroyed in a fire and I have a couple of 65W.

To anyone contemplating stripping the element out of theirs for a service be advised that they do contain what appears to be asbestos and it's quite friable so only attempt this if you're aware of the risks and precutions. You don't want 5 million fibres in your lungs just to save a tool you can get for a fiver at the boot fair.

If you want adjustability with no backlash then a trap a pair of thrust bearings either side of the part pre-loaded with a belville stack. You can adjust the force of the pre-load to suit your rigidity requirements (and need to prevent it self-adjusting) and you'll be able to adjust it for level with no need for locking nuts etc.

I would adjust out the twist by loosening the outermost pairs, using the innermost pairs to make your adjustments then bringing the outermost pairs of feet into contact. You might do the last bit whilst keeping the level at the same end to be sure that you don't impart any unwanted twist.

Andrew, do you still have this tap? My friend called me today wanting to chase out a 1/2"-22 thread on an old DSG lathe he's restoring. It's a thread for a detent plunger.

What is wrong with just a fine thread screw? Differential screws are all well and good but they have a woefully small range of adjustment. A fine thread screw say 10mm x 1mm pitch will give a range of adjustment which is the effective length of the screw itself and easily adjust to better than the 1 thou you require. In fact, I use a sensitive level on parts supported on 1mm pitch thread screw jacks and find no difficulty adjusting to tenths with a 4" long spanner on the hex head of the jack.

Yes, that is what I mean, the taper and the star wheel are separate. I don't think that the taper itself is split.

David, the original clutch is cast iron and 2-pieces. YOu might be better off emulating that, I suspect that brass will be a bit grabby and poor to release. Here's a pic of the original:

Mellor gear.

Don't lose that gear BTW they are the devil to make.

One of those cheap 30a plasma cutters will whizz through 2.5mm stainless.

I thnik that the reason it will never be concluded is because people work to limits and standards that they find acceptable to themselves. Perhaps through informed choice, apathy, lack of experience/understanding or any other reason. If your lathe is turning out parts that work for you and make you happy then why put more effort in?

BTW I also had my Eagle surface grinder on casters. The casters were fixed to a 12mm thick square steel plate and the grinder on top of that. I used to wheel the grider out of the corner, do some grinding and then push it back into the corner to save space. I figured that since the grinder had a chunky square base and single column, it would not be affected by this. One day I was part-way through grinding some part or other, I had to stop and move the grinder on it's casters to get access to something. When I went back to grinding the whole grinding pattern had changed. Now, I have the machine fixed in it's position on the solid floor.

I can tell you since rebuilding machines is my hobby (I mean grinding, scraping, alignment not just clean and paint), and since concrete cutting, breaking grinding is my profession where I've had to grind plant room/water tank plinths to +/- 2mm over several metres, and because when I'm in the process of rebuilding (but not the alignment phase) a lathe will typically sit on casters,

1. Concrete isn't flat. Even a properly laid power-floated floor is very unlikely to be flat enough that you can move a machine sitting on four points and not have it twist. For your average tamped/trowelled slab - no chance.

2. If you sit a machine like a Bantam on casters and move it any amount, the twist of the bed will change. As a matter of fact, I have sat a bantam on casters whilst in the rebuild process and ran a test whereby I had a dial gauge reading bed twist whist it was being wheeled around and that dial gauge was swinging like a metronome. Here it is on it's 6" 200kg casters after I wheeled it out into my garden for a photo.

So if you're asking can you use a lathe that's on casters the answer is - certainly you can. If you're asking can you move it and expect it to hold alignment, even to move it one way then move it back - certainly not. For most people it's not really an issue because their lathes are not aligned anyway.

Edited By Pete Rimmer on 19/01/2023 22:11:31

Get some Araldite 2013. Industrial strength.

If you want to know for sure just set up your screw on your surface grinder and grind the last turn of thread on it down to half diameter to expose the full profile. You can then set a camera up directly above it, take a zoomed-in photo and then open the pic on your pc and use some software to measure the angle.

That last 2.5mm of thread is of little practical use to you anyway.

I'm sorry if you're offended but if you're going to further a pressure-group's agenda onto a forum that's unrelated to the topic you'll have to accept that some people might take exception and give you an undesirable response. Your smiley face at the end of your sentence suggests that you knew it might be contentious and you were posting for effect.

Bottom line is, if you don't want an emotive response, don't start a thread on an emotive topic on an inappropriate forum.

Yep and Vic just propagated their cause one step further. Well done Vic.

Their page is badly configured too when it pops up their cookie/analytics options if you click one of the switches by accident (they colour it blue when 'off', opposite to usual) it automatically accepts all cookies, closes that pop-up and hits you with a donate pop-up instead.

I have actually done what you are contemplating on my FN22 milling machine (a clone of the Deckel just like your Alexander is). It's rather a forbidding prospect and since I'm still in the rebuild process I cannot tell you how successful it has been except to say that the motor does actually run.

**link**

I am fully expecting sooner or later to have to exchange the motor for a modern one but the challenge of re-configuring the original was too great to pass up.

Mike,

As above, for 0.5mod all you do is take your tooth count, add 2 then divide the result by 2. So your 120 tooth gear would be 61mm diameter.