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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
24/05/2021 17:29:24

That would make sense John because the shape wuld change on smaller tooth counts.

As I said I have no clue about cutting these types of gear. I do recall being most upset when I found out that my 33DP gear cutter (a very rare involute size) turned out a lovely cycloidal gear

I have catalogued the first twenty cutters and they are a mic of DP, CP and module. Some are actually marked as module but an insensible size (like 0.505 mod) until you realise that it's exactly 1/16"CP. Seems to be no rhyme nor reason and I guess conventions have changed over the years my collections span.

I will continue to catalogue them and see what I end up with. I have about 20-25 ratchet/escapement hobs to measure also. Some are new in the box.

Thread: Todays Car Boot Bargain!
23/05/2021 14:20:49
Posted by Rob McSweeney on 23/05/2021 13:53:36:
Posted by duncan webster on 23/05/2021 13:26:04:

I think you'll get more joy searching for Pittler lathes, looks like a re-badge job to me.

http://www.lathes.co.uk/pittler/page5.htlm

The Pittler lathe on that page is the exact one the OP has just bought. Got the same marks and scratches.

Thread: Cycloidal gear hobs
23/05/2021 14:16:46

I'm (slowly) working through them. I have cycloidal hobs that conform to sensible numbers in DP, module and metric circular pitch so far. For instance the latest one I've measured only makes sense for it to be called a 2.25mm circular pitch. The module would be 0.7163.

I've knocked up a spreadsheet so I can input the normal pitch and it spits out all the conversion numbers. I was using the chart from Davall which is very good but I have loads that just don't appear on it.

Using the microscope shows me that I have not so many cycloidals as I thought, some are all kinds of weird shapes. For instance I have one which is triangular shaped, straight sides 55deg rounded root and crest just like a Whitworth thread (except a straight sided hob will produce involute teeth) and a pitch of 0.0394" or 1mm CP. Somebody somewhere must be chuckling at me.

I would dearly love to get some insight from someone who has hobbed cycloidal gears in the past. Some of my cutters have tooth counts on them too.

Thread: New use for a slide rule
23/05/2021 13:43:01

I have a slide rule but I have no idea how to use it. Then again, I'm only in my early fifties

Thread: Bench (tool) grinder
23/05/2021 12:21:53
Posted by Michael Gilligan on 22/05/2021 20:30:40:
Posted by John Haine on 22/05/2021 20:18:03:

... I've never seen a resin bonded CBN wheel! ...

.

Out of my price-range, I suspect ... but here goes: **LINK**

https://www.superabrasivetools.com/resin-bond-cbn-grinding-wheel/

MichaelG.

There are budget ones Michael, I bought a 8" one for under £50 to use for grinding abrasive stones flat. I also bought a couple of 5" tapered edge ones for my tool & cutter grinder for sharpening hobs. They were just over a tenner each.

amazon link

Edited By Pete Rimmer on 23/05/2021 12:24:53

Thread: Strange result from the forum search ...
23/05/2021 10:45:25
Posted by Michael Gilligan on 23/05/2021 10:05:43:
Posted by Pete Rimmer on 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.

.

Sorry, Pete ... I don’t understand the relevance of that.

My problem is that the search gave me one result and that result is wrong.

MichaelG.

I don't know if it's relevant at all just wondering. After looking at it again I don't think it is. I wondered if the default view for the "thread start page" option in account preferences would affect the order that the search engine 'sees' the page numbers, thinking that perhaps changing the option might reverse them.

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.

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