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Member postings for Pete Rimmer

Here is a list of all the postings Pete Rimmer has made in our forums. Click on a thread name to jump to the thread.

Thread: Cast Iron stress relieving
15/03/2019 14:59:39

There's no point scraping the feet THEN stress-relieveing it because the scraped faced will need doing again afterwards.

If you're going to do it - rough-machine it, stress-relieve, machine again then either scrape it or do another round of stress relieving and machining then scraping. Forget fire pits and barbeque tricks for a reference surface like this, take it to a professional and have them heat soak it in an oven so it gets even heat all over then controlled cooling. Anything else is just rolling the dice and hoping.

Personally I would have liked to see a lot more thickness on the sole of the one in the pic above. It's going to be very thin once it's machined past the skin.

Thread: Inverter
12/03/2019 19:31:43

I have made literally dozens of starts an hour on my lathe and milling machine when cutting threads, with no ill-effects. That's on single-phase, 3-phase and DC motors. I would not worry about it at all. If you have a VFD then set a gentle start ramp and you'll see on the display that the amps don't go much above the no-load running figure.

Thread: Precision division plates
10/03/2019 06:59:13

Newbould indexers use a Hirth coupling and they are supremely repeatable.

07/03/2019 11:17:21

Regular dividing plates are suitable for all but the very finest of work but one often overlooked aspect of them is the concentricity of the hole circles to the centre hole. If it's not the indexing will be all over the place.

I bought a set of three used plates for my IXL head and found that although all the hole circles were concentric to each other the centre hole was a good 5 thou out. Thankfully I had to bore it bigger to fit and had enough meat on it to get it central.

06/03/2019 20:30:36
Posted by Neil Wyatt on 06/03/2019 18:13:14:

If you want perfection, the sun isn't as accurate as you might want (google analemma) accelerating and slowing down over the year. You also need to get your polar alignment accurate. I'd use a star, but remember to work using a sidereal clock, not a solar one.

Neil

I googled anal emma by mistake. Got some very interesting results....

Edited By Pete Rimmer on 06/03/2019 20:32:14

Thread: J&S 540 Dwell Lever
06/03/2019 19:44:03

Mine was a simple brass casting drilled for the spindle and cross-drilled for the pin. There's a reasonable image of one here:

J&S540

Edited By Pete Rimmer on 06/03/2019 19:46:32

Thread: Milling Collet Jammed in Taper
05/03/2019 20:41:28

I saw this happen once before to a guy I know. He complained about the same problem and that the nut had come off but the drawbar wouldn't release. Bashed it for a day and a half before he realised there was a second nut on the drawbar which acted as a lock-nut for the longer first one.

He loosened that second nut and the collet popped out.

Thread: Atlas Sphere Lathe
03/03/2019 20:33:33

If it's a close copy of the Atlas then you could get an idea of the gearset from the threading chart.

Atlas 10

I would say that £150 is a very fair price if the machine is basically sound. I wouldn't pay much more than a couple of hundred no matter how nice it was.

Thread: J&S 540 Dwell Lever
02/03/2019 19:39:21

I had one of those but for an older machine so it was in brass. Threw it out a few months ago along with all the other 540 bits.

TBH for the half-hour's work it would take to make one I would not bother sourcing a genuine part.

Thread: Imperial acme threaded rod
21/02/2019 15:52:00
Posted by Paul Appleton 1 on 21/02/2019 08:15:34:

Mcmaster-Carr will no longer accept orders from the UK. Try finding a LH Acme 5/8x10 tpi leadscrew and nut in Europe!! The old Colchester lathe I have originally has a 5/8x5 TPI thread on the crosslide. This is not even mentioned in most data books. By replacing with a 10TPI I would have had a direct read dial. Wow! how 'modern' is that?

BR, Paul

The reason is that it's a 10tpi pitch .200" lead 2-start thread.

Thread: Lead Screws
20/02/2019 21:15:14

There's a very good chance that if you can cut your screw with the tool running away from the chuck, your lathe leadscrew is probably barely worn (if any at all) in that direction.

Of course, the only way to know is to map the wear in the lathe leadscrew

20/02/2019 20:10:01

Before attempting to effect any re-cutting I suggest that you map the condition of the screw in both directions to record the wear on each side. Set up a tenth-reading dial indicator and use it to record the actual travel at each turn or half-turn of the screw. Do this in both directions because if the flanks are worn in both directions and you only machine one flank you'll still have a loose spot where the other flank is.

A few things to note:

If your lathe leadscrew is worn you will create a screw that has the same wear characteristics as the lathe screw, so you need to use a lathe with a very good screw to make an accurate screw for your mill.

If you map the wear on the screw then machine both sides of the thread you'll have a screw with an asymmetric threadform and you'll need to produce a matching nut or some kind of backlash compensating system for the nut you have.

Thread: Denford Viceroy 280 motor and inverter
18/02/2019 11:56:16
Posted by Andrew Evans on 15/02/2019 22:33:11:

Pete - do you mean removing the variable pulley (which is attached to the motor) or the other fixed pulley or both? The belt is currently a 28 mm wide toothed belt - like a timing belt, not sure if that is need or I could use something else.

I took the motor and variable speed mechanism off today - it was a big job really. I have decided the wiring is too dodgy. I can't use the variable speed pulley anyway without the full VS mechanism. I now have to choose the best motor frame size to buy, work out how to fix a pulley onto the motor shaft and then what belt to use.

Yes that's what I meant. I actually fitted one of those Denford setups to my milling machine and whilst it gives great variable speed it also suffers vibration. It's common as the belt and sheaves get older as I understand.

I'd find a nice used 1.5kw motor and vfd if it were mine. The mount plate is large enough to be re-drilled for various sized motors as I recall.

Thread: New to metal lathes - bore sizes?
15/02/2019 20:57:59
Posted by Chris Evans 6 on 15/02/2019 20:03:23:
Posted by Pete Rimmer on 15/02/2019 16:49:07:

The smallest lathe I know of which qualifies is a South Bend Heavy 10 which passes 1-3/8" (34.925mm) through the spindle.

Edited By Pete Rimmer on 15/02/2019 16:49:22

That may depend on the year of the "Heavy Ten" my 1942 model sold about 6 years ago was only around 1 1/8"

Good point. It's not the year, but the spec but yes there were some heavy 10's with the smaller bore just like there were some other sizes with the larger. The larger bore are by far the more common and identified by the 2-1/4" spindle thread.

Thread: Colchester Headstock Sleeve
15/02/2019 18:51:14

One of my lathes is Jarno 12. I wish I could find an adapter for it.

Thread: New to metal lathes - bore sizes?
15/02/2019 16:49:07

The smallest lathe I know of which qualifies is a South Bend Heavy 10 which passes 1-3/8" (34.925mm) through the spindle.

Edited By Pete Rimmer on 15/02/2019 16:49:22

Thread: Colchester Headstock Sleeve
15/02/2019 13:00:33
Posted by Howard Lewis on 15/02/2019 10:47:44:

Jarno tapers all have the same taper, 2 degrees 15 minutes.

Howard

Are you sure? I'm no Rachel Riley but I get 2.8664 degrees included angle.

14/02/2019 23:40:04

Without drawing it up in CAD your adapter sound awfully close to #13 Jarno taper.

Thread: Denford Viceroy 280 motor and inverter
14/02/2019 10:23:25

Since the VS has the variable speed belt and pulley setup which is a real power hog not to mention a source of vibration especially when they get old, I would give serious consideration to removing those pulleys, and the VS speed control, and fitting standard vee pulleys in it's place. You'll get smoother drive and more efficient power transmission to the spindle.

Thread: Buying lathes direct from China
13/02/2019 19:34:07
Posted by Barrie Lever on 13/02/2019 18:47:29:
Posted by Rainbows on 13/02/2019 15:49:38:

Was checking the price for a BT300 (roughly equivalent of SIEG SC10, bit below a Chester Craftsman in weight).

Compared to a Craftsman I would save £1000 and get a roughly same specification lathe. Price is after delivery and VAT, etc.

Anyone got warning stories of their experience importing heavy equipment? Would be the heaviest thing I have bought abroad by 200 kilos so could go wrong who knows.

Rainbows

I have not imported a lathe from China but I did import a laser cutter, there are a lot of pitfalls and some hidden costs over and above the VAT, duty and insurance.

The big problem is if something gets broken in transit then the whole thing will be a PIA.

Regarding CE marking a number of Chinese factories have no respect for CE marking, full CE marking is a resonably involved game, but there are approval houses that will do back door approvals for just about anything.

One German company that I know was told by a Chinese manufacturer that he thought CE stood for China Export !!! see below.

https://www.cnc-step.com/infos/diy-hobby-cnc-router-kit/

My final word is dont do it unless you can afford to gamble the complete cost, in case the whole deal goes down the pan.

Regards

Barrie

The CE compliance mark and the China Export mark are deliberately similar to fool unsuspecting people into thinking they have bought a CE-marked item. Once you know, it's easy to tell them apart. Quite simply if you continue the C around to make it an O, on the CE mark the edges will meet but on the China Export mark they cross over each other.

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