Member postings for Graham Wharton

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Graham

For quick identification, the metric ones have a groove cut round the base.

This is a metric collet

And this is an imperial collet

There are 4 in the metric set 6, 10, 12 and 16 and 4 in the imperial set 1/4", 3/8", 1/2" and 5/8" for the small S type chucks.

Actually there are 5 metric as you can also get an 8mm, but they are rarer than rocking horse sh*t and i've never actually seen an 8mm threaded shank cutter that would go in them.

Hope this helps

Graham

Hi Neil,

Yeahh, there was never any intention of bad mouthing them at all. All suppliers can have quality issues, even the more reputable ones. As usual with this supplier, they dealt with the issue promptly and completely to my satisfaction, so all credit to them.

Also, it shouldn't take long to work out who the supplier is as there only seems to be one supplier of ACME dies in the entire world, as i found out!

Graham

Supplier promptly sent me a replacement die.

Which produced a much better result on my test piece.

Result !

Graham

Nigel,

I'm starting to think I will just finish the thread completely in the lathe too. I'm using a good full form insert from Sandvik. Its a Corothread 266 insert in the right toolholder with the right shim, so should give me extremely good results. The only problem is I have to run it quite slowly and I don't get the best of finishes going slow. I was hoping that the die would just take the burs away and give me that pristine finish. I might look at ways of mounting the piece with extra headroom at the end of the thread so I can thread at a higher speed without worrying about crashing as soon as the insert leaves the thread at the end. I guess I could also use my variable speed to keep it fast for the majority of the threading operation and just slow it down at the end so I can control when it stops easier. I'll try another test piece going to full depth. Ive threaded full form to full depth on the lathe for metric threads without a problem, for some reason, maybe increased surface area of the acme thread, the cuts were not as clean as usual which pointed me towards using a die to cleanup.

Graham

Murray,

I did try it yes. I had run the piece on the lathe to 90% of the depth with a single point tool first. Then ran the die down it. Prior to running the die, the trough in the thread had a reasonably flat bottom. The first pass left a groove along one side of the trough. I reversed the die and ran it again, this time it put a groove in the other side of the trough. So i'm left with a W shaped trough.

When I first looked, i had thought like you, perhaps to keep the stresses down, each tooth cuts its own slightly different V, all at slightly different positions in the trough so the end result is a "reasonably" flat bottom. But I don't think this is the case.

Thanks

Graham

Actually, here's the picture from the vendors website. I'm not overly convinced the one they photographed was much better than mine. I'm certainly not picking out any flat crests on the cutting teeth there.

Thanks

Graham

Hello,

Just looking for some opinions. Received this brand new ACME 1/2 x 10TPI HSS die from one of the mainstream ME suppliers today. Any thoughts on the quality, and its ability to form a decent looking ACME thread.

The intention was to thread 90% of the depth using a form tool on the lathe and clean up with the tap. The test piece I have just run with it came out less than ideal IMHO.

Thanks for the advice. I'm pretty sure this will be returned to the supplier tomorrow.

Graham

Before I go along the "I'll make one" route, does anyone know a source for replacement straight scribers for height gauges? I've managed to find a few cranked ones, but no straight ones.

Graham

Clive,

It is a wedge type scribe point, not a round one. It doesnt come out well in the pictures. Heres a closer view.

If I mount the scriber below the clamp bar it still does not reach the table. If it was designed to reach the table, the scale on the height gauge would start from 0. As it is the scale starts at 1.5 inches. If I put the height gauge to 1.5 inches, the top of the clamp bar is 1.5 inches from the table. There is only approximately +/- 1mm adjustment in position of the scale, so theres no way it can work any other way, than with the scriber mounted in the top of the clamp bar.

Graham

Jason,

A massively exagerated illustration, but if the scriber is blunt, you will scribe a line higher than you wanted to.

Maybe on a blunt scriber it equates to a tenth, a thou, maybe 10 thou I have no idea.

Graham

Thanks for everyones suggestions. They've been really useful.

Ive actually just been out and had a look at the height gauge again, with the intention of measuring it up for a new cranked scriber however as you can see from the photos, its designed to have a straight scriber and by the looks of it, designed not to measure anything below about 40mm. I guess I would place small items on a 1-2-3 block to raise their height.

You can see here on a 2" block, its reading 2", so no need to manually add numbers as I originally thought.

Calibrating the metric side with a 50mm slip.

Calibration is done by loosening the screws on the vernier plates, which are slotted and adjusting them to suit.

I was just thinking aloud. I haven't ever tried sharpening the end of my scriber in the height gauge. It had occurred to be if the end was dull, or badly radiused, or not ground correctly, I could actually be scribing a line somewhat above my zero reference.

i.e if there was a 5 thou radius on the end of my scriber, all, all my scribed lines would be 5 thou greater than any height measurements made using the under side of the scriber.

Cheers guys. The finger on mine doesn't go down to the base. I'm presuming at some point it had the old cranked finger replaced with a straight one. I stick a 1 inch gauge block under it and calibrate it at the 2 inch mark.

If I use the fine adjusting knob on the height gauge to slowly drop the finger down until it touches, its quite often tricky to actually determine the point at which it touches, and I guess you could have the same effect when zeroing to the base. You could crank it a thou too far and actually have lifted the front of the height gauge up, or alternatively what you think is touching is actually slightly above base. You loose all feel for the "touch down" point when using the fine adjustment. This isn't just a calibration thing. It would be exactly the same if you were using your height gauge to measure the height of a block and needed to touch down the finger on the top of the block.

This is on a chesterman height gauge with has coarse adjustment by disengaging the head from the feedscrew and sliding the whole head up and down, or fine adjustment using a knob on the base to spin the feedscrew. If I attempt to touch down onto a gauge block using the coarse adjustment, the head drops back into the nearest thread in the feedscrew which moves the head.

If I get the height gauge close to the right height using coarse adjustment, then press down on the base and use fine adjustment to drop the finger onto the top of the item being measured, I can kindof feel it touch, but not definate enough for it to be repeatable to the thou.

I suppose I could try getting it to what I think is touching, then if I can slide the gauge block in and out from under the finger, but not feel any noticeable up and down play when I try and rattle the gauge block, that would probably work.

I guess its all in the technique.

Do i have a 40 year old gummed up height gauge that has "lost its feel".

My height gauge has been at the back of my tool cupboard since I acquired it. And Ive only just tried to start using it. Can you tell

Graham

Hi guys. I just wanted to get the general opinion on the correct way to set and use a height gauge.

Lets say for example I want to scribe a line on a block at a known height.

I have put the height gauge on a surface plate, and then put a gauge block next to it. I swing the height gauge finger over the gauge block and drop the height until I can just feel it rub on the top of the gauge block as I swing the height gauge over it. I am doing this using the under face of the height gauge finger. I then adjust the vernier on the height gauge to calibrate it. Is that the right way to calibrate the height, or should I do it until the point strikes the side of the gauge block and then back off slightly.

I can then set the desired height on the height gauge and swing it across the face of my item scribing the line.

Is this the correct way?

Presumably the scribed line will be offset by half of the radius of the end of the height gauge scriber. As the height gauge was zero'd on the underneath surface of the finger but the line was scribed at the point. Does this matter, I can't gauge what the likely difference would be.

How do people care for their height gauge fingers, do people regrind the points, and if so is there a preferred method.

If doing it using my method, then the flatness of the underside of the finger, having the finger mounted horizontally, and having a point ground at the very bottom of the finger with a small radius are all key to getting an accurate measurement out of it.

Sorry if this is a dumb question, but i've searched online for help on how to use one, and they don't cover these specific questions.

Thanks

Graham

The statement "Due to long time storage some sizes may have little bit rust (about 2%), please check photos." rings alarm bells for me.

Luke,

The M1 has a separate idler wheel used for tensioning the belt for the table feed. It might make for an interesting crossover arrangement.

Its different to the Junior picture I posted which doesn't have any mechanism to tension the belt, hence the stretchy polycord.

Graham

Ahh, sounds like the M1 operates slightly different to the Junior.

To engage power feed on the Junior I pull up on the lever at the right hand side of the knee.

I disengage power feed by rotating the lever in the middle of the knee anti clockwise.

Two dogs can be positioned anywhere on the front of the table to automatically disengage the power feed, which it does by pressing down on a pin in the middle of the knee. Depressing this pin has the same effect as rotating the disengagement knob anti clockwise.

Looks like we still have a selection of left to right and right to left people though.

Just checked in the manual and it confirms anti-clockwise is the correct rotation.