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Jig Borer in the home workshop

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Andrew Evans30/05/2017 17:30:06
345 forum posts
8 photos
Does anyone here use a small jig borer for model engineering purposes. I have the opportunity to get a Downham but not sure how much I would use it. I already have a Seig KX3 CNC mill but no drill press.

Any advice is much appreciated. Andy
Bob Stevenson30/05/2017 17:43:11
579 forum posts
7 photos

This is best thought of as a 'precision micro milling machine'...we have one in the workshop of Epping Forest Horology Club and use it for making tiny precise components for watches and sometimes clock parts. I have used it for 'crossing out' clock wheels,..ie., cutting out the spokes. It needs extremely accurate and careful setting up and is NOT the same as a small milling machine in application. Also, it would make a poor substitute for a drilling machine in terms of convenience of use.....

.........Personally, I would consider it of only passing use for making anything that does not require small precise components,...but extremely useful for making watch components. Only you can judge the complexity of what you are going to make and decide accordingly.

Tractor man30/05/2017 17:43:56
426 forum posts
1 photos
Hi Andy.
I have a shaftesbury jig borer which is very similar to the Downham I believe.
I use it for drilling obviously,but also do light milling work on it. I have a face mill and a really nice boring head as well as morse taper adaptors. I'm just in the process of adapting a 30 int shank to carry a centre scope which I hope will help with ease of setting up.
I'd say get it and find a use for it.
Regards Mick
Andrew Evans30/05/2017 17:53:05
345 forum posts
8 photos
Many thanks. I intend to continue to make model IC engines so small parts but not watch part small. Lack of accuracy has been an issue for me but that is more down to my lack of skills. Andy
Stephen Benson30/05/2017 18:43:01
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203 forum posts
69 photos

Brilliant machines I have been using My Downham Mk111 for the last 15 years perfectly suited for model engineering quite capable of milling with a 16mm end mill the quality of the Downham is excellent the table and dials are the best I have ever seen a joy to use and as a bonus they are designed to be sat next to rather than stood by.

Edited By Stephen Benson on 30/05/2017 18:43:50

Andrew Evans31/05/2017 08:52:22
345 forum posts
8 photos
Cheers Stephen, do you have a DRO on yours? Andy
Bikepete31/05/2017 10:43:59
239 forum posts
34 photos

Apologies in advance if this is against the rules (if it is, mods feel free to delete) but seeing this thread it seems relevant - I have a friend in York (not a forum user) with a Downham/Elliott mini jig borer for sale. I've only seen pics but it looks in good shape. Message me if interested and I'll put you in touch.

Stephen Benson31/05/2017 11:25:29
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203 forum posts
69 photos
Posted by Andrew Evans on 31/05/2017 08:52:22:
Cheers Stephen, do you have a DRO on yours? Andy

Mine had a cheap Chinese DRO which did not survive many Winters in my garage My Mk3 has a great system to use with the dials you can set the table pointers after zeroing the dials to save counting the turns I found this much better than a DRO (usual backlash techniques apply) so if it does not have a DRO do not buy one until you have tried the built in system even when I had a working DRO I used the dials for final positioning

Andrew Evans31/05/2017 16:40:52
345 forum posts
8 photos
Thanks. Cheers Bikepete it's the one in York I am looking at - nice machine. Andy
Ramon Wilson31/05/2017 22:03:07
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1319 forum posts
382 photos

Hello Andrew,

I note your post and question with interest as I have been using a Linley Jig Borer in my workshop since the 1970's and (despite a current hiatus in machining) also have an interest in making I/C engines

The Linley was the original from which the Downham was built (under licence possibly?) and mine is the Mk1 without the power feed to the quill.

I was told by the seller (GW Machine Tools) at the time that these were mainly used for precision 'spotting' of holes in parts for further drilling elsewhere. Whilst I respect Bob Stevenson's opinion I purchased mine from the outset with the intention of using it as a milling machine and as such it has served me well for the last forty odd years in that function. I made all tooling including collets from silver steel and later Arne B01 tool steel (which is very similar) and left them in the un-heat treated state, all of which are still perfectly serviceable to this day. I can genuinely say this little machine has machined many many components over the years and will serve you just as well in my opinion. I find it's only limitation at times is the low head room from spindle nose to workpiece but so far have always found a way to get round that issue. It would be nice too to be able to tilt the head at times but again this can be got round.

The collet shape is similar in form to an R8 but approx half the overall size. The form is a Shaublin design I believe. None were available when I purchased the machine and it would be several years before I found out the actual specification. I measured the internals of the spindle very carefully and made test pieces to establish the sizes and angle of taper. I believe somewhere up the loft is a drawing of that that I made at the time - if that would be of use I will gladly copy it for you.

I have just tried to post this but get a message that it's too long and to split it into two - that's a new one!

Back in a sec then - Ramon

Ramon Wilson31/05/2017 22:25:13
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1319 forum posts
382 photos

Agh - I've just lost the second bit!! I'll try again.

Some pics of it's life

Stripped down for first painting

First refurb circa 1975

Second refurb and new table circa 1995

The tooling made and still in use

Another mod made early on was to remove the spindle and cut the drive shaft off. This was drilled through (from each end) to take a draw bar and the spindle drilled through too. A collar to reconnect the two has worked without fail over all this time

As said it's proven to be a real asset over the years and has produced countless milled parts - some quite large - without protest. The largest end mill/slot drill used has been 12mm or 1/2 shank - ie 9/16 and 14 mm dias. It's produced several 5cc I/C engines as well as all the parts made so far for a Bentley rotary - still languishing under the bench I'm afraid.

Providing the one you seek is in reasonable condition I have no hesitation in saying it will serve you well given it's limitations. Good luck with your purchase Andrew - I hope this helps allay any doubt you may still have.

I guess I should point out I have absolutely no connection with the seller of this machine.

Regards - Ramon

Bob Stevenson31/05/2017 23:23:17
579 forum posts
7 photos

Ramon,....notwithstanding my comments on amateur jig borer use above, that really DOES look like a very nice and useful machine beautifully restored!....and I would love to give it a try with some tricky clock parts!

 

.........In the EFHC workshop our Aciera F1 has more or less supplanted our jig borer now as it offers more easy setting up and facilities etc.

Edited By Bob Stevenson on 31/05/2017 23:25:16

Andrew Evans01/06/2017 00:07:46
345 forum posts
8 photos

Thanks Ramon, great restoration work - looks like you did it in your front room smiley. Andy

Ramon Wilson01/06/2017 09:35:27
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1319 forum posts
382 photos

You are welcome Andy - no that's not the front room but the third bedroom. My workshop was in there for several years before my ever tolerant wife finally got fed up with swarf in the hall! No not really - I built a larger workshop outside and moved everything in there.

I forgot to mention - in the first refurb you may note the collet nose piece is home made which gave a rather longish overhang of the cutters so new collets were made to suit the original hardened nose piece that came with the machine. I mostly use the 1/4, 6mm and 10mm side lock end mill holders for general milling but can always revert to the collets - which are threaded internally to take the cutter thread) for the odd occasion.

Bob - I have very little desire for machining at present but time was I would have loved an Aciera type mill. When I think of what has been produced on this over the years it has been a reasonable substitute though.

Working on my last I/C engine I really needed the ability to swivel the head so as a seventieth birthday present I bought an Amadeal bench mill - so far it has not been used !!

Regards - Ramon

Paul H 102/06/2017 09:29:30
37 forum posts

Hello Ramon,

That is an awe inspiring renovation you have done. It looks along with the tooling you have made for it, an excellent subject for an article in MEW. I also suspect you have a very interesting workshop to write about.

Regards, Paul

Ady102/06/2017 09:54:55
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5089 forum posts
736 photos

Wow. She looks fabulous

Bob McDougall17/03/2018 00:15:32
45 forum posts
280 photos

Just had delivery of this beautiful Downham mini borer machine from a very nice Rob in Norfolk. Full set of collets and 2 axis DRO. Compared to the huge Beaver Ive just sold this is a much more suitable machine for me. to make clock and lock parts on. My intention is to CNC convert it which the beaver was just overwhelming to do. This only took four big men to get out of a van. The beaver needed a 2ton crane on a lorry. First impressions are very good. Once on the workshop floor two of us could manouver it by hand. Hoover motor. will have to see if its 400V or 220 as only have 220 3PH but its a foot mount not flange so should be easy to change. happy .

as delivered day 1

John Haine17/03/2018 07:51:39
4671 forum posts
273 photos

Very nice machine. Now I see what the Myford VMB was based on.

A 400v 3 phase motor is just one that is delta connected to a 220 volt per phase supply.

Bob McDougall17/03/2018 21:01:25
45 forum posts
280 photos

The Downham Hoover motor was stamped as 220/440 and sure enough under a very dust filled plate probably never removed on the motor were six terminals. It had been run on 440 3PH.

Downham motor

The origional 440V star configuration 1-3-4 as the centre, 2,5,6 as the 3 phase.

440V connections

The new 220V delta configuration. 1-6, 2-3, 4-5. with the 3 phase on 2,5,6 or could be any of the three bars.

220V connections

Next problem the 240V lamp was on a transformer so I just disconnected it from the rear terminal box. next problem the side on/off switch was a solenoid overload current trip but was a 440v solenoid so just buzzed at 220. 440V current breaker

So I just jumped the blue-blue, white-white, red-red, the inverter handles overload currents so this is not needed.

AND I was cutting metal !

downham borer drilling

Yes I will use as centre drill when Im less excited.

Emgee17/03/2018 21:36:21
2426 forum posts
290 photos
Posted by Ramon Wilson on 31/05/2017 22:03:07:

The collet shape is similar in form to an R8 but approx half the overall size.

Back in a sec then - Ramon

Ramon

I believe the arbor/spindle type you have is an R0 , same as used on a British mill I sold some time ago.

Emgee

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