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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: Milling table regrind
06/07/2018 18:05:43

Grinding a mill table can often do more harm than good. A bit of surface pitting won't hurt once you've stoned the surface rust off but milling or grinding it can easily make a banana of what once was a straight table.

Thread: Am I getting an irritable old git?
01/07/2018 20:09:57
Posted by larry phelan 1 on 01/07/2018 19:44:18:

Perhaps that should be "Queens English"?

As in the dialect they might speak in New York's largest borough?

01/07/2018 18:06:18
Posted by martin perman on 01/07/2018 17:51:12:

I was taught to speak, read and right proper and I do expect others to do the same, I text queens English with all of the necessary punctuation in the correct place and if my daughter, 37, sends me a text I ask her to do it again if its it text speak on the basis that I don't understand.

I think we should form a club of old gits.

Martin P

If this isn't some kind of subtle joke, it's quite funny anyway

Thread: Is this true..?
30/06/2018 07:07:50
Posted by Hopper on 29/06/2018 12:26:37:

Nuts are about 1 x diameter thick, usually. Some cylinder head nuts etc about 1.5. I was taught 1.5 x diam. is considered max strength but 2 x is a bit of a safety margin.

Also, was taught that tapping into aluminium, use a coarse thread as fine will pull out easier. Some textbook theory is at variance with this but over many years I have seen BMW motorbikes with countless stripped fine threads in cast aluminium on drain plugs, filler plugs, cylinder studs and the like. But Harley-Davidson, who use coarse threads in aluminium, seem to last 80 years and more without stripping out.

Good quality aluminium will hold fine threads no problem. I re-built a bike engine to allow for 3x the power via a turbo and I drilled & tapped the cases for 12mm x 1.25 pitch head bolts which is extra fine (originally M10 fine) and the main bearing bolts (from M9 fine) . They were torqued to 75lbs/ft in 2007 and that engine's still going strong today.

Thread: Threadcutting in the lathe - help please!
20/06/2018 19:31:19

One thing that catches many novices out is that often threading a piece of stock will raise a burr which makes you think that the thread's not deep enough when in fact it's binding on the major diameter when you try the nut. You start to wonder if you've got your sums right because you've hit the full depth and the nut is nowhere near fitting so you keep taking cuts until the nut fits but then you find it's a sloppy fit and you don't know why.

Use a caliper to keep an eye on the OD after you have taken a few passes. If it's started to grow because you've pulled up a burr just carefully run over it with a flat file taking long smooth strokes as the part is turning. On a vee thread it won't take many strokes but on an acme/trapezoidal thread you might have to go at it several times to file the burr down to the correct OD.

Thread: Which type of pin
09/06/2018 05:49:30
Posted by JasonB on 08/06/2018 20:56:37:

Nige is making one of these but with a square head

A 'crotch centre'.

Thread: Does the alignment of halves of scroll lathe chuck matter?
05/06/2018 20:34:48

The negative of the L4 stamping at 8 o'clock on the right side is quite clear to see at 4 o'clock on the left. You have the orientation correct in the pic, just flip one side over on top of the other.

Thread: gear cutters
05/06/2018 18:31:06

You don't even strictly need a button. I made my first single-point cutter by first making a fly cutter of the same diameter as a button then cutting both sides of a piece of gauge plate with the head of my mill tilted to give the form with some relief.

05/06/2018 00:38:56

If you get stuck Frank I could possibly cut those gears for you, though you would have to cut any keyways required as I have yet to lay my hands on a broaching cutter set.

Thread: How to maximise material removal rate on a mini lathe?
01/06/2018 17:45:25

1. Get a decent piece of HSS

2. Grind a RH roughing tool with a ridiculously steep top rake and generous front relief.

3. Watch it slice off material like butter on your low powered lathe.

Thread: Source of good HSS lathe tool blanks
27/05/2018 12:40:30
Posted by Phil P on 26/05/2018 17:24:30:

I have started using "Stellite" tool bits in my tangential toolholders. Much more resistant to heat and wear than any HSS I had been using previously. I did try the Crobalt and that seemed OK, but then found some 1/4" square Stellite.

They turn up from time to time on a well known online auction site.

Phil

I make 'one shot' tangential style holder from small nubs of stellite. I mill a notch in some hot rolled steel and braze the stellite on the end tangential style. They get sharpened by grinding the top face.

Did you know that if you get a new piece of Deloro Stellite it will have a tiny notch ground in one edge on the end. The notch is to tell you that the tool is strongest if you grind it with the notch on the top.

Thread: Morse taper spec.
26/05/2018 14:27:46

I've yet to hear and tales of woe of anyone getting Jarno tapers wedged in such a fashion, and they are all made the same angle of taper.

Thread: Paint for Colchester Lathe
21/05/2018 20:31:14
Posted by pa4c pa4c on 21/05/2018 08:43:11:

The only problem nowadays is finding good brushes at the right price. Surprisingly to me, rollers work well too.

What constitutes a 'good' brush? I've always run away from any kind of painting job partly because I find it tedious and partly because I always seem to struggle to get any kind of a good result. It could be that I have never tried to paint with a good quality brush.

21/05/2018 07:26:40

You can get decent results with roller and brush. It's how this was painted:

https://www.dropbox.com/s/1jizgb3szllic6h/bantamafter.JPG?dl=0

 

Edited By Pete Rimmer on 21/05/2018 07:28:25

Thread: Myford Super 7 VFD Controls & Clutch Switch
12/05/2018 20:35:04

What is the microswitch for Nick? An electrical interlock for the belt lever?

Thread: Metric ML10 lead screw threadform
25/04/2018 16:38:33

If you hand-grind a threading tool to within the half-degree difference between acme and trapezoidal flank angles you're some kind of superhuman. It's only half a thou difference at the tip of the thread at the pitch we're discussing.

25/04/2018 10:51:23

I just found a NOS set of half-nuts on eBay and the thread is quite roughly cast into the metal (zamak, possibly) half-nut. I guess that makes the half a degree half-angle difference immaterial.

https://www.ebay.co.uk/itm/MYFORD-ML10-HALF-NUTS-3-0-PITCH-FOR-METRIC-LEADSCREW-/352300339399

25/04/2018 10:05:37
Posted by not done it yet on 25/04/2018 09:30:22:

ACME is TPI and metric trapezoidal is pitch and never the twain shall meet - or at least they shouldn’t!

True that, but then my Denford lathe had a cross slide screw that was 1/2" OD x 2.5mm pitch. They just used the same material and cut a 2.5mm thread in place of 10tpi. Weird things happen.

25/04/2018 09:30:04

Pretty easy to get the angle with a gear tooth caliper and some basic trig. I guess I'll grind a 30 degree tool in preparation and check the original screw when it gets here.

25/04/2018 08:52:57

It's certainly 3mm pitch.

 Assuming the screws were made in house, they could easily have used the same tooling for both.

That's what concerns me, or rather that they might have used a 8tpi insert and set the lead to 3mm.

 

 

Edited By Pete Rimmer on 25/04/2018 08:53:27

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