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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: ACME thread identification question.
30/08/2019 08:50:18

What tap you need depends on the diameter of the screw. Hopefully it'll be 12mm then you'd need a TR12 x 2.5 LH (Trapezoidal, 12mm diameter, 2.5mm pitch, Left Hand) tap.

However, there's no rule to say it has to be an ACME thread. For instance the Denford lathe, a close relative of the Boxford range (they were once the same company) uses a cross slide screw which is 1/2" diameter, 2.5mm pitch and neither ACME Nor Trapezoidal thread form but "modified square section" thread.

I'd try to find a drawing for the screw or the nut.

Thread: Help milling an angle
28/08/2019 11:03:16

Double-post..

Edited By Pete Rimmer on 28/08/2019 11:03:37

28/08/2019 11:03:15

Your 60 degrees angle is two 30 degree angles so all you have to do is clamp the plate down flat on the table (on stand-offs) and nod the head 30 degrees, do one side then flip the plate over. I like to use scrap 1/2" MDF for this kind of thing, lay the MDF on the bed, plate on top, couple of clamps and you know you can mill away without milling the table.

Thread: ACME thread identification question.
25/08/2019 20:33:06

The drawing calls for 7/16"-10 LH so that's surely what it will be.

25/08/2019 14:59:15

Your problem might simply be a matter of the wear in the nut having caused burrs that the worn screw rides past but the new tap does not.

Measure twenty threads on the screw. If it's 50mm you have a metric screw, if it's 50.8 (or 51 to a steel rule) then it's an inch screw. Inch screws are 7/16" x 10TPI LH

Thread: 4 jaw chuck axial allignment
19/08/2019 08:28:09

What are you using as a gauge? Simply touching two opposing jaws together and observing the light gap should tell you if they are parallel or not.

Thread: Garden shed find
18/08/2019 22:07:56
Posted by Nigel McBurney 1 on 18/08/2019 18:32:31:

.A machine tool fitter once told me the gears for the hi/low box are tufnol and easily damaged by operators changing speed before the spindle stops,his comment was "I have replaced an awful lot of those gears so wait till the spindle stops" .

That's true I made a Delrin gear for a Meddings MF4 (I think) for someone to replace a stripped one. Actually I made a pair so I have a spare one kicking around someplace that just needs finish-machining.

Thread: Myford
18/08/2019 20:13:18

More modern machines might have rubber wipers but traditionally they are mostly felt for all sizes of lathe.

Thread: 4 jaw chuck axial allignment
17/08/2019 19:03:09

Start with a faced-off part and use a dial gauge on the face to check it every time you clock it in radially. Or keep the faced-off face against the chuck and keep it there with a dead blow when dialling in the OD.

Thread: Can Anyone Help Me to Identify This Very Old Boiler Please?
14/08/2019 19:28:19

I think that is one of those ones you have to give a good kicking because someone dropped a screwdriver in the safety valve.

Thread: Chuck out of true
06/08/2019 22:31:01

3 thou is pretty fair for a used 3-jaw.

Thread: Adjustable 3-jaw chuck designs
05/08/2019 23:08:59

My everyday 8 inch chuck is held on 3 bolts on the backplate with no register. Hasn't shifted since I fitted it and it's done a lot of turning of all kinds.

Thread: Collet Chucks out of true
05/08/2019 23:03:53

I would pre-set the compound for cutting the 8 degree inside taper half-angle then mount a DTI so the probe is measuring at exactly 9 o'clock on the inside taper when looking at the chuck face. It also must be exactly on centre height (so that's dead on centre height measuring the point nearest the operator).

Now turn the chuck and watch the DTI swing through it's full range. Note the highest and lowest readings (which should be opposite each other) and stop turning the chuck when the dial is exactly half way between them (so the high and low points are at 12 and 6 o'clock). This is the point where the taper angle should be correct for measuring. Run the compound in and out and start making small adjustments until you can sweep the taper without the dti moving. Lock the compound and check the dti again and if it hasn't moved you can mount a tipped tool (once again dead on centre height - it's extremely important that this is observed) and use a skim cut to true the taper.

Thread: Machine tool reconditioning
05/08/2019 22:41:22

Sadly, Slideway Services packed up last Christmas Manny.

Thread: Collet Chucks out of true
04/08/2019 18:44:59

Good collet chucks and collets are very repeatable. Far better than a 3-jaw.

04/08/2019 11:45:22

How hard is the material? Too hard to turn a new taper with carbide? That's what I would be looking to do if it's not getting returned.

Think of it as making yourself a collet chuck except someone else has done the roughing out

Thread: Any uses for an old tired lathe bed
04/08/2019 10:40:30

I'm sorry yes it is the wrong link. I will remedy that right away, though I can't edit the previous post so I'll put it here.

EDIT: here is the link I meant to post.

Buy the steel to make the shank from here

Edited By Pete Rimmer on 04/08/2019 10:46:21

03/08/2019 20:06:36
Posted by Phil H1 on 03/08/2019 19:47:11:

David/ Peter,

Do you have an idea (perhaps from measurements with straight edges and feelers etc) how much wear is on the bed you have? Peter, how much wear was on your S7 bed scraping exercise before you started?

Phil H

Phil, see the image below. wear is marked in ten-thousandths of an inch.

03/08/2019 19:52:20
Posted by David Kenyon 2 on 03/08/2019 19:39:29:
Posted by Pete Rimmer on 03/08/2019 18:45:27:

My first scraping project was a S7 bed. The simple shape makes for a great first project.

That's an idea , I might have a go at scraping it.

Scrapers are easy to make. Buy a sandvik tip and make the rest. Get a 1500-2000 grit flat lap disc off ebay (or get a set of three different grits for about 12 quid) and fix it to your chuck face with double sided tape. Turn lathe at 300-400 rpm and use it to sharpen to 5 degrees negative.

03/08/2019 18:45:27

My first scraping project was a S7 bed. The simple shape makes for a great first project.

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