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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: Cycloidal gear hobs
23/05/2021 10:33:12
Posted by Michael Gilligan on 23/05/2021 10:18:21:

Very intriguing, Pete

What module sizes are they ?

MichaelG.

Ah, now there's a question. Most of them have only numbers so I am laboriously measuring each one and labelling them. I have a nice little measuring microscope which I have fitted with a mount for the hobs and tenth-reading dials so that I can accurately take pitch and form readings. Some are module but most of the numbered ones so far conform to DP sizes. Some are marked with the module or pitch. I will be working through them today so I'll have a good list. I'm using paper tags at the moment whilst I gather the bits to make an etching pen.

 

Edited By Pete Rimmer on 23/05/2021 10:34:11

Thread: Strange result from the forum search ...
23/05/2021 10:01:13

Does the forum search return result pages in order of date ascending or descending? It's an option in your profile.

Thread: Cycloidal gear hobs
23/05/2021 09:55:49

Does anybdy even use these any more? I have a bunch of cycloidal gear tooth hobs of 8mm and 10mm bore but after doing a search I don't see any used ones for sale which means they are either undesirable or unobtainable, I suspect that it's a bit of both. I also have a few ratchet cutting hobs.

Having no interest in horology or instrumentation I don't suppose I will ever use them. They don't take up much space so keeping hold of them is not much of an issue but on the other hand I'm conscious of the fact that with the advent of additive machining in metals these hobs might soon become completely obsolete that is if in fact it has not already happened.

If these things are still in common use somewhere I should like to find out where. Alternatively, if there's a common range of gears used I wouldn't be averse to producing cycloidal gear form bar stock for people to part off their own gears from but again I wouldn't know where to start looking.

It just seems such a waste to have them sitting in a box for the next twenty years (hopefully, at least) for them to then end up in a skip.

Looking for ideas, suggestions etc.

Thread: Bench (tool) grinder
22/05/2021 20:44:01

Thanks for the correction John. CBN is very prevalent in fact a lot of what is called diamond is not natural diamond at all. We use a lot of diamond products at work electroplated and sintered segment.

22/05/2021 19:12:01

That looks like an electroplated diamond wheel rather than a CBN. It could be electroplated CBN of course but typically the CBN wheels are abrasive mixed into a resin bond and rely on erosion to keep them sharp. Electroplated wheels have a thin coating of diamond fused to a metal carrier.

Thread: screwcutting in a ML7
22/05/2021 13:19:26

Check the tooth count on your stud gear.

Thread: Would Pete please contact me.
17/05/2021 19:21:05

That is a nice piece. I have a pair of direct-reading 0.0001" heads by Shardlow that I have fitted onto my H&W measuring microscope to replace the 0.001" Moore & Wright ones but they are much larger diameter than this one.

Thread: Lathe run out
16/05/2021 11:10:48

I make adjustable machine feet by welding large thick washers to the heads of bolts The washers go against the floor and I use flanged nuts underside of the feet, unless the feet are themselves tapped.

As for putting the level on the flat tops of the prisms - This won't allow for wear but it will let you see if the bed has twist. T

he prisms will have been ground in the same setup as the ways (or at least they should have). There's no other efficient way to do it.

Thread: Does anyone know what this is for?
11/05/2021 17:25:37

Some better angle shots would be most helpful George, for example face-on with the camera about 4 feet away at a height between the top and bottom shaft. Handle end and working end. That would show the relationship of the various workings quite well. Your first view of the extra pics would be pretty good if the camera wasn't held so high.

You know, until the pic with the guy's hand on the top adjuster even the scale was difficult to tell. I thought it was a floor-standing item.

10/05/2021 22:59:49

Well, I don't think the author is a member here but if he is and he feels offended then I apologise for that.

Thread: Lathe run out
10/05/2021 20:32:36

If I were you I would:

Check the bed for straightness with a sensitive level. Adjust to suit (if it's possible). If you have no level or it's not adjustable (maybe it's on three feet) just carry on down this list.

Chuck up a stout piece of ally in the chuck (perhaps 2" dia and 6" long) take skim passes and check for parallel. If the bed is not twisted and the part dosn't turn parallel then you have no choice but to loosen the headstock and adjust.

Once you have it turning parallel time to adjust the tailstock. Measure the tailstock ram with a micrometer. Turn the piece in the chuck to the same diameter. Bring the tailstock up to the part you have turned.

Put a mag base on the saddle with a tenth-reading dial gauge. Put the dial gauge against the side of the ram and move the saddle so it crosses over to the turned bar. It should read the same. If it doesn't adjust using the off-setting adjuster until it does.

Now do the same but running the dial gauge along the top of the parts. If the tailstock is low shim between the body and base to suit. Check the ram is level with the dial gauge or very slightly rising (never falling).

If you do all that you'll be about as good as you can get.

10/05/2021 18:47:28

34" of 1" bar is basically a noodle. It could be anywhere. Even if it were held by the tailstock centre it would still not turn parallel because the centre would whip. This is a time that you need to use a travelling steady.

Edited By Pete Rimmer on 10/05/2021 18:47:57

Thread: Does anyone know what this is for?
10/05/2021 17:29:23

It 's a subject-piece for a "who can take the worst photos" competition. Honestly you couldn't take less useful photos if you tried.

Thread: DTI contact points
08/05/2021 11:13:15

I bought a 'carbide' tip from ebay and found that the stem was easily shaved with my carbide scraper. Not carbide then. Seller tried to get me to accept a refund but I kept it and added appropriate feedback so that others may be warned.

Thread: Where to find a *good* optically flat mirror?
07/05/2021 17:23:34
Posted by Tendor on 07/05/2021 13:43:56:Hume's book on autocollimators mentions that reflectors should be flat "within a few millionth of an inch" (~ 75 nm)

My mounted mirrors came with certification stating the measured flatness as 3 millionths and 7 millionths of an inch.

Thread: Shipping to the EU - beware!
06/05/2021 17:55:41
Posted by Samsaranda on 06/05/2021 10:20:55:

A few years ago I mailed a couple of castings to myself, in the UK, from Australia, had been there on holiday and the castings would have put my baggage seriously overweight. Don’t ask why I bought castings in Australia, the wife gave me enough grief over it. The castings arrived at the Gatwick freight handling centre and couldn’t be released until I had paid the admin fees and VAT on the items, I was not best pleased having to pay VAT on my own possessions.

Seems to me the only thing different between you buying something in Aus and having them ship it, and buying something in Aus and shipping it yourself is the person putting it in the box. What reasoning do you use that makes it different with regards to import charges?

Thread: Help please!
27/04/2021 23:40:57

Hi Diane,

My condolences on losing your dad it must be a trying time. I had to clear away my dad's workshop stuff and I kept some but most of it I had to get rid of.

Your dad's little lathe will have more sentimental value than monetary I would expect and most of the value is because the Myford name was made very popular by the later model 7 and it's iterations. I think that you'd do well to get a couple of hundred for it in that condition.

One thing I do see in the pic is what looks like a fixed steady tucked in the tray under the tail end of the bed. Those are not common and might be worth a few bob. I see it also has a threading dial (long vertical tube with a gear on the bottom, right by the letter F). Might be desirabl to someone.

The cover on the left end should open to expose some gears. There should be loose ones with it so they can be swapped about.

Good luck with your sale, I hope it does well but don't expect too much.

Thread: Does anyone know what this is for?
26/04/2021 23:33:57

I think that eye bolt has a piece of rope tied to it with some kind of tension spring attached.

Frustrating having only one angle of view and most of the business end out of sight.

Thread: tapered slots
18/04/2021 23:40:56
Posted by geoff rimmer on 18/04/2021 22:36:17:

im in the process of making a 24 stop dividing head thingy, (dont know what theyre are called), its a 5" chuck mounted to revolve on a heavy angle plate to be used vertical or horizontal, behind the chuck is a flange with 24 tapered slots cut into which a tapered stop locates, tapered milling cutters are big bucks so im looking for alternatives to buying one? any ideas??

The plate with the slots is called a masking plate. Used for rapid indexing.

Thread: Gear
18/04/2021 22:53:42

No problem Mark, whenever you can.

BTW even though the Hardinge stub gears are famous, Hardinge UK certainly used full 22DP gears I have a factory drawing for them.

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