Hydraulic Copying Attachment – Micrometer Adjustment

[Anonymous]

I'm currently using my hydraulic copy attachment to screwcut tapered threads. I'd like to control diameters a bit more consistently than I've done in the past. On the attachment is a silver knob with indents marked from about a thou to 60 thou. In this picture it's the silver knob above the lettering 'Colchester':

The manual says it's a micrometer for adjusting the final depth cut. Simplistically I would expect moving it would move the slide slightly thus adjusting the cut depth even with the follower fixed. But it doesn't. So I don't know if it's broken or I don't understand how it works.

Can anyone offer any insight into it's operation?

Andrew

[Anonymous]

[Michael GilliganParticipant @michaelgilligan61133]

Assuming that I have found the correct patent: The action of item 17 is described

**LINK**

https://worldwide.espacenet.com/patent/search?q=pn%3DGB1376623A

MichaelG.

[David Davies 8Participant @daviddavies8]

Gents

The patent says: the depth of cut is adjustable by moving the fulcrum axis 5 of the lever 4. Does this mean that by changing the fulcrum the setpoint going to the summing junction is reduced so that the travel required to achieve a null position is reduced?

I'll get my coat!

Dave

[Anonymous]

Posted by Michael Gilligan on 29/04/2020 23:35:54:

Assuming that I have found the correct patent…..

It is indeed the correct patent. Thanks very much for posting. Thanks to the patent I've been able to get the micrometer adjustment working in the way I expect. Tomorrow I'll give it a go when I make another tapered thread plug.

Note that I said I've got it to work, I'm still not sure how it works. I'll have to sit down and study the patent. The trouble with patents is that they're written in a stylised way such that everything needing to be patented is described but in such a way as to make it difficult for others to understand and implement.

It's interesting that the patent is dated 1971, not long before the attachments were rendered obsolete by CNC lathes.

Andrew

[Michael GilliganParticipant @michaelgilligan61133]

I was certainly having trouble with that patent, Andrew … and I’ve read a lot of them.

Hopefully you have a great advantage, in that you have the device before you.

… You will also have great motivation to comprehend it.

Happy reading.

MichaelG.

[Alexander Smith 1Participant @alexandersmith1]

Seeing this thread and the pictures reminded me that I've got one of these in the back shed (think mysterious cavern of treasures unexplored for too long). It came my way via the local scrapyard and I planned to fit it to my Harrison 140 but, like so many projects, it never got going, principally because the hydraulic unit was missing. Does anyone have (or can point me to) a manual for the copying unit or let me have a spec for the hydraulic unit – is this something completely specific or could I use an alternative?

Sandy

[Anonymous]

Posted by Alexander Smith 1 on 01/05/2020 12:25:21:

…like so many projects, it never got going, principally because the hydraulic unit was missing.

Do you mean the tank and pump for the hydraulic oil?

Andrew

Edited By Andrew Johnston on 01/05/2020 15:55:01

[Alexander Smith 1Participant @alexandersmith1]

Hi Andrew, thanks for responding

yes, the tank and pump for the hydraulic oil were missing when I found it. I have a small hydraulic pump that powered an actuator cylinder on a hefty piece of equipment and wondered whether it might be suitable but I have no idea of what the original was. A manual for the whole attachment would also be useful to ensure that nothing else is missing.

Sandy

[Anonymous]

I have a spare tank and pump that might be available. I've never used it so I don't know if it works, but it doesn't look in bad shape.

IIRC the system runs at about 350psi, much more than that would result in things going pop.

Andrew

[DC31kParticipant @dc31k]

Posted by Alexander Smith 1 on 01/05/2020 20:31:13:

…A manual for the whole attachment would also be useful to ensure that nothing else is missing….

The attachments come in various sizes and the hydraulic requirements of each size may differ.

You may need to identify more fully what you have.

lathes.co.uk has the usual over-priced manuals available but they seem to start at the 300 series. Rondean has manuals also, and for the smaller series. Google also threw up dgrdesigns as a source, but their website appears to be unwell. There is a set of instructions for 300 series on eBay, item 352938828050.

Put 'Hepworth copier manual' into Google and look at images for more leads. It is also worth searching for 'Hepworth tracer manual' as an alternative term.

See also Andrew's thread here:

https://www.model-engineer.co.uk/forums/postings.asp?th=119990

As a starter for 10, the manual for the 300-series (Chipmaster, Bantam) says the pump is 0.6 gallons per minute flow and the relief valve is factory set at 300 psi.

 

Edited By DC31k on 02/05/2020 08:38:46

[Alexander Smith 1Participant @alexandersmith1]

That's a very kind offer, Andrew, but before you do anything let me dig it out of the back shed and take some photos and check condition to see whether it is still worth bothering you – it's been in there for years and I don't want to waste your time. Thanks also to DC31k, I've been hunting through google and the sites it throws up and I should be able to buy a manual but I can't see information on the different models so difficult to determine exactly what I have. As I said to Andrew, I'll dig it out and take some photos and dimensions.

Thanks for all your help. Sandy

[Alexander Smith 1Participant @alexandersmith1]

Hi Andrew, found the copying attachment in the back shed and after a little bit of cleaning it looks OK. Everything seems to be there and moves freely so it should work OK. The toolpost was put "somewhere safe" which means I can't find it at the moment but it is around. I can't see anything to indicate which model or size it is – the only number on the casting is C19787 which I presume is the serial number. Does this look like your one – in which case your spare hydraulic unit should be suitable if you are happy to part with it. Let me know whether you need any other information to confirm what model it might be. Thanks Sandy

[Anonymous]

This is the pump unit:

Looks to be complete, but never used. A possible issue is the motor is 3-phase and looks like it is configured for star only, without digging into the motor.

Your copy attachment looks almost identical to mine, albeit with some parts missing. Right side of mine:

The obvious bit missing is the toolpost, although this is a self-contained unit attached by three screws (3/16" BSW I think). So it could be replaced with a home brew toolpost. The bent handle for the indexing stop is missing as is the adjustable stop on the body. But neither of those would be difficult to make. Left side of mine:

Looks to be the same as mine, nothing missing. I've never worked out what the coarse adjustment stop on the left side is for. Unless it an "oh s**t" stop that provided a last chance stop if, for instance, the follower misses the pattern.

An obvious question is where are you based, I'm near Cambridge.

Andrew

[Alexander Smith 1Participant @alexandersmith1]

Hi Andrew,

thanks for digging out the pump- I'm sure a coat of paint and a little TLC will serve. I have a converter so should be ok or a friend is very good with digging out star points and then I could use a standard inverter. I see that 415v inverters are becoming much more reasonable but I've never used one but another possibility I have the toolpost- just couldn't find it to appear in the photo. I'd removed the indexing stop as part of the cleaning and only realised that It was still lying on the bench when I'd taken most of the photos but it is there in the first one ( which I took last). I'm assuming that the bent lever is just a length of bar with a knob so even I should manage that. Presumably, the connecting pipes are standard hydraulic items?

i'll drop you a PM to discuss how we can sort thinks out if that's ok.

sandy

[Anonymous]

As far as I'm aware the indexer handle is just a bent bit of metal with the thread on the end. The ends of the pipes on the spare pump just have small brass unions on them. I've no idea if they're standard fittings. I've never taken mine apart to have a look. The manual shows three hydraulic pipes, and there are three connections at the tank end, but only two appear at the attachment end. The pipes appear to be plastic so shouldn't be too difficult to get replacements. The manual also says the motor is dual voltage, so it may well be, just not with the standard means of swapping.

Andrew

[Author]

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