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Member postings for Chris Trice

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

Thread: ER16 Collets from Ebay
24/04/2022 13:07:48

Surely this all depends on the nominal size of the collet and the size of the tool being held. I can't see a 10mm tool held in a 10mm collet in a clean chuck needing a lot of torque to hold the tool concentrically? You'll need more torque the further the tool held goes away from the nominal size of the collet due to the amount of distortion that needs to occur.

Thread: Myford induction hardened beds
24/04/2022 12:51:54

Am I right in saying the hardening only extends into the bed a few thou deep?

24/04/2022 02:58:27

Mine is a green IHB with the plate saying so and the middle of the bed is an off white.

Thread: Imperial v Metric Measures
09/04/2022 18:19:20

Metric is the rightful heir to the throne and already used in every progressive country and culture. Units of dimension are linked to volume, weights and indirectly temperature, and universally adopted by all the sciences. Based on decimals, the maths is a lot easier too. I work happily in imperial but once "our" generation dies out, the world will be metric rather than clinging to archaic and arbitrary measurements based (allegedly) on nothing more than the length between a 16th century monarch's finger tip and his nose. It's a done deal so don't shoot the messenger. As a bit of interesting trivia, an English bishop, John Wilkins, (1614-1672) invented the concept of a universal integrated measuring system that was the foundation of the metric system. The only people keeping imperial alive is the model engineer.

Thread: Mini-lathe saddle casting error.
01/01/2022 15:19:50

Put a straight edge across the surface and slip a feeler gauge between the part and the straight edge. That should tell the story.

Thread: To harden or not to harden that is the Question
27/12/2021 20:09:04

Female threads are in compression and stronger than their matching male threads which are trying to sheer off the central core of the stud. It's why high tensile bolts can have mild steel nuts.

Thread: 43 TPI
27/12/2021 19:49:07

Yes, it says so in Tubal Cain's excellent book on Drills, Taps and Dies.

26/12/2021 11:56:51

Apparently the smaller Thury threads are BA form anyway. The larger are more akin to metric.

https://www.sizes.com/tools/thread_thury.htm

26/12/2021 11:48:35

That's a thought. The thread is so fine though I'm not sure the actual thread form is going to play a big part. I have to say looking at the thread, it's more akin to a regular 55 or 60 degree thread form than the rather more rounded BA thread.

26/12/2021 03:38:46

devilbiss.jpg

26/12/2021 03:25:15

I know Everything Airbrush as they are the official inheritors of the Devilbiss brand and spares. One of the guys there worked for Devilbiss assembling the airbrushes on the production line. It's not 0.6mm. I took a silicone mould of the internal thread and then compared it to various thread gauges viewed through a jewellers loupe with an engraved scale. As mentioned, 44 gauge is too fine and the 42 gauge is too coarse. Incidentally the originator of the DeVilbiss Aerograph airbrush was American but they have been manufactured exclusively in England for more than a hundred years, essentially unchanged apart from modern materials being introduced. The external air valve thread as mentioned is 3/8 UNEF and the thread in the handle (still available) is 5/16 x 32. The thread I'm chasing (see what I did there?) is the thread in the forward part of the body. All the dimension of the airbrush appear to be imperial (needles are 3/64" diameter rather than the more common 1.2mm. Unless anyone can suggest another thread with a virtually identical pitch, 5BA (43 tpi) is all I've got.

24/12/2021 03:35:58

Thanks everyone for the replies. I managed to get the thread calculator working and managed to get it within 1/10th of a tooth over 1" which is more than enough as I'm only machining about 3/8th" of thread. In answer to the question what's it for, I'm machining the body threads on an old Devilbiss airbrush and although the bore is about 11mm, the thread is the same as a 5BA machine screw. I suspect they may have used 5BA Coventry die head chasers as a cutting tool. It's not 44tpi and it's not 42tpi. The only thread I can find inbetween is 5BA which is 43tpi. I may braze up a tool from a die head as a cutting tool. The important thing is it's close enough to do the job.

23/12/2021 15:39:22

I've got to cut a 5BA thread on something which is a horrendously inconvenient 43 TPI. Can anyone suggest a set of change wheels running off an 8 TPI lead screw (Myford Super 7). A tiny error might not matter but I need to be close. While my maths is good and the principles understood, this is taxing me. Comparing notes will help.

Thread: Wobbly slitting saws
30/06/2019 01:12:13

I'll probably get vilified for sounding like a broken record but I've found the cheap import ones are the worst offenders by far. I usually end up making a wide arbor to grip the cutters nearer to their periphery but of course you lose cutting depth.

Thread: Myford Super 7 Top Slide Base - Alternatives?
30/06/2019 01:08:23

I built the Hemingway kit about ten years ago. It's a nice bit of kit BUT I've never had cause to use it and it's languished in a drawer ever since. I ended up custom making a beefier and larger top slide of my own design that still allows taper turning.

Thread: water supply
17/06/2019 00:53:05

For the record, it's a myth that lemmings fling themselves off cliffs. That misinformation originates with Disney.

Thread: Ebay 'photos'
10/06/2019 20:44:15

The one that gets me is people who sell chuck jaws separately who also have the jawless chuck they obviously came from for sale as well. It's like selling a car without the doors and offering the doors separately. It just comes across as miserly and penny pinching. Just sell the matched set of pieces together.

Thread: Myford boring bar help
01/06/2019 19:27:22

I can't remember if it's Sparey or Mason but the practice employed for setting the Myford Boring bar is to use a micrometer set to measure half the required bore and half the boring bar shaft diameter. I've found it is possible to gently tap the wedge piece to let go of the cutter slightly, then tap the cutter to the right position before re-wedging it tightly. The measurement is taken from the cutting tip of the cutter to opposite side of the bar. Not the most convenient set up but inexpensive.

01/06/2019 11:50:52
Posted by Andrew Tinsley on 31/05/2019 11:34:51:

Hello Mark,

It looks as if your boring bar is faulty, as others have said, do talk to Myford.

Andrew.

No, it is not faulty.

31/05/2019 03:46:25

TB is right. I have one of these and one hole holds the cutter while the other has piece that is flatted on one side in a slight taper. The cutter is wedged in place quite firmly but adjustment is tricky.

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