Member postings for Pete Rimmer

I don't have a shaper but I love my hobbing machine and I use it often.

Stick with it Paul, you'll have a lot of fun finding out what works and what doesn't.

Error of 77 millionths of an inch is exact enough to satisfy common tolerances. Not mathematically exact as you say since you have to divide the Pi by DP to achieve a recurring decimal.

Edited By Pete Rimmer on 28/05/2021 20:17:40

Where abouts ar you William? My lathe does 27tpi on the gearbox you're welcome to use it if you can get to North Kent.

Otherwise I could hob a change gear for you.

Incidentally if you have a chart for DP threads see if theres a way you can add a multiplier to achieve 85DP that's the exact pitch for 27TPI

Pete.

Whoops - I guess like most I just assumed Kevin was in the UK.

Value suggestions might not be relevant for your locality Kevin, but I do wish you good luck with the disposal and hope that you'r not finding it too difficult sorting through your dad's stuff.

Pete.

Depending on the model of Craftsman it could be the headstock misaligned on the bed, or the bed is twisted somewhat.

Excellent!

I also have a 10EE, I didn't know of anyone else in the UK that owned one until just now.

That's a gorgeous looking example Kevin. Worth more than any of the values quoted so far in this thread due to it's condition and the multitude accessories that can be seen. Your dad must have had great pride in his workshop.

Pay attention to the smaller items that he owned, going by what's visible in the picture it's likely that there are some valuable tools in there which you might pass over as insignificant.

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.

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

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.

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

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

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.

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

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

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.

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.

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.

Check the tooth count on your stud gear.