BCA / Boley Jig Borer Tooling

[pgp001]

Well I have had almost no success in obtaining any original collets or tooling for my new little machine, apart from one 1/4" internal threaded collet, so I decided I would have to make my own. I am not bothered as I get as much satisfaction out toolmaking as I do model making.

So here are some photo's and a few words to go with them.

First job was to decide how many blanks I needed and cut the material which in this case is EN8 steel.



In actual fact I decided to up the quantity so I cut even more material so I could make a few extra gadgets. By now they were all faced up and centre drilled.



Next they were all roughed out to slightly oversize dimensions using a carbide tipped tool to shift the material quickly.





From now on the three jaw chuck was put away and all operations are done between centres, here I am taking the main shank down to 11mm diameter finished size.





The blanks are then reversed in the centres, and the driving dog grips the still oversize area where the drawbar thread will eventually be, now I can use the topslide to add the tapered part of the collet.







So now we flip em all back round the other way and turn the threaded part to the finished diameter.



Then screwcut the M9 x 1mm drawbar threads.
I initially set up the metric conversion quadrant for this thread, but then remembered the 33 or 34 tooth spindle gear trick so you dont need a fancy gear train, the error is so tiny you would be unable to measure it anyway, I have a Meek screwcutting clutch on the Myford, and once the half nuts are engaged you just keep flipping the lever adding the next cut and let it run up to the stop and trip the feed, if you have never heard of this gadget, look it up. It has got to be one of the all time best additions I have ever made to a lathe.







The plan was to screwcut the threads and then run a die down to finish and de-bur them, so i sent off for a die advertised at the very reasonable price of £5 on a well know internet auction site, I decided to play safe and do a test piece first, and boy am I glad I did.
The finish was total crap and the new die basically wrecked the screw cut thread.



The die was solid, ie no split for adjustment, at first I thought that was the problem but then I found that the die could be filed with a needle file just as if it was plain un-hardened steel ( I suspect that is exactly what it was). The vendor quickly agreed to a full refund and I then bought a genuine HSS one for three times the price, it is true that you get what you pay for and buying cheap means buying twice. The new die worked perfectly and finished my threads so they were a perfect fit in the drawbar, but it cost a few days whilst waiting for the post.

Next up was adding the keyway down the side. This was done on the Alexander milling machine and was fairly straight forward.





So there we have a set of blanks all ready for turning into tools that can be used on the jig borer.



More to follow soon.
Phil

[Jo]

Looks like someone is going in to competition with me for the most number of BCA tools 

Jo

[Don1966]

Phil, I thoroughly enjoy tool making, and will follow till complete. Very nice work and photos.

Don

[pgp001]

Don

In reply to your PM and for anyone else interested, this is the information for metric screwcutting on a Myford with a QCGB.

I take no credit for this, it has been freely available on the internet for a while.
http://homews.co.uk/page346.html

I am sure he wont mind me mentioning it, but John S (see members list) might be able to help people who need the additional change gears.

The logic can be applied to any lathe, I find a spreadsheet is the easiest way to manipulate the figures and see what it spits out.

Phil

[tangler]

With a few more change gears you can cover the whole metric range including BA - as Phil says, a little work with a spreadsheet makes it easy.



cheers,
Rod

[pgp001]

Finally finished off the tooling this evening.
Here are a selection of photo's.

First off a pair of drill chucks in 5/32" and 1/4"



Four slitting saw arbours in 1/4" 3/8" 1/2" and 5/8"



A 30mm boring head, a 1½" flycutter and a 4mm spotting drill.



A Starrett wiggler, an edge finder, and a 1/2" dia ball race, all used for locating edges and holes etc.



An ER20 collet chuck, a DA200 collet chuck and a DA300 collet chuck.



And the special reamers for finishing the internal tapers on the DA collet chucks.





Phil

[Don1966]

Phil, you have been busy. Beautiful job on the tools, you must have had an assembly line going. Great work. 

Don

[Jo]

  Ok, it must be too early in the morning for me, why do you need 3 different types of collets for her? I would have thought that the DA300 does everything that the ER20 does. I would have chosen the DA200 collet system just because I have a full set of those but why do you need them and the DA300?


Good point, I have not yet got a pointer tool for the BCA... I normally set up on the edges of the work... Flycutting...  would I do flycutting on the BCA   

I recognise that boring head  So what nice boring bars do you have for it? (that don't flex as much as the originals do.)

Did I mention I had a larger drill chuck hidden away for the BCA.... and I was thinking about maybe making an arbour with an M14 * 1mm thread to let the Cowells goodies fit the BCA.. but that looses head room 

Nice setup  You have no excuses now... When are we going to see some progress on Agnes? 

Jo

[Jo]

And can you explain the use of that ball race for setting things on the mill... I don't know that one .

Jo

[pgp001]

Ok, it must be too early in the morning for me, why do you need 3 different types of collets for her? I would have thought that the DA300 does everything that the ER20 does. I would have chosen the DA200 collet system just because I have a full set of those but why do you need them and the DA300?


Good point, I have not yet got a pointer tool for the BCA... I normally set up on the edges of the work... Flycutting...  would I do flycutting on the BCA   

I recognise that boring head  So what nice boring bars do you have for it? (that don't flex as much as the originals do.)

Did I mention I had a larger drill chuck hidden away for the BCA.... and I was thinking about maybe making an arbour with an M14 * 1mm thread to let the Cowells goodies fit the BCA.. but that looses head room 

Nice setup  You have no excuses now... When are we going to see some progress on Agnes? 

Jo

The collet chuck question, why all three ?. I suppose the answer is "because I can" I have full sets of collets in each type so have the choice of which I use, I can also set up with multiple tools if I have different holders for them and only have to swap the holder between operations.

The fly cutter will get "light duty use only" as I dont want to damage the spindle key with shock loads.

The boring head will be used with 1/4" diameter solid HSS tool bits ground to shape.

The ball bearing is brilliant for locating diameters and edges, say you need to find the centre of a round bar sticking up from the table.
Run the table up to the spinning ball race in the Y axis, as soon as it touches the ball race it stops spinning. Set DRO to zero on the Y axis.
Repeat the process in the opposite direction and then use the 1/2 function to set Y to zero.

Then do it agina for the X axis and you are over the centre of your work with the spindle.
The bearing diameter matters not in this case, the DRO does the maths for you. Mine is 1/2" diameter so when finding edges I know I am 1/4" away when it stops spinning.
I initially doubted the accuracy of this method but was pleasantly surprised at how repeatable it actually is.

Phil

[Jo]

Ok: so it is not that dissimilar to what you do with an edge finder or a wobbler. 

I have a wobbler on my BCA but I had picked up one of the modern centre finders and had happily been using that on the Prazimat Mill. However  I managed to slightly stretch the spring when I forgot that it was not a wobbler and not as forgiving when I miss judged the clearance over the work as I traversed from one side to the other: now it wobbles more than it used to  . So I am now questioning what value the new type of centre finders are over the original wobbler design.

I have a cheap and nasty original wobbler which has four gadgets, including ones with a ball end and cylinder ends, (I also have a couple of tool maker made wobblers on 1/2" shanks). The original BCA one is the only one I have with a barrel end... and it is my preferred one of all the centering devices

If that is the small boring head from where I think it comes from it takes 6mm diameter tumbo... Most annoying because I keep acquiring broken centre drills and they are all 1/4" and not 6mm so cannot be reused
--------
I would like to have a DA200 collet chuck for the BCA but I suspect that it would end up being used on the GHT dividing head as a collet chuck, rather than on the mill. Must get around to making a converter to be able to mount the Cowells chucks onto the GHT dividing head, which would enable me to use the Cowells DA200 on it any way  .

For repeatablility I have a number of arbors bored to take standard tooling sizes that I put bits in and then swop between them, rather than disturbing the setting by undoing the collet chuck. I have a similair set up on the harrison where I use multiple Clarkson Autolocks rather than taking out the tool each time. (Yes it is potentially a very expensive way of doing things but the second came to me for £5 and it was worth that for the collets that came with it  )

Jo

[ths]

Such wonderful choices! Phil, we should all be so lucky.

Cheers, Hugh.

[pgp001]

If that is the small boring head from where I think it comes from it takes 6mm diameter tumbo... Most annoying because I keep acquiring broken centre drills and they are all 1/4" and not 6mm so cannot be reused

Jo

My boring head was indeed made for 6mm toolbits, but its dead easy to open the holes out to 1/4"

The ball race edge finder is really useful and I find it gets more use than any of the other types I have in my armoury, I have one of the laser types as well but still cannot decide if it was money well spent.

I made the special bearing holder for the Boley, but on the Alexander I just use a short stub of ground steel with a ball race on the end and hold it in the machine collet, I made three actually 1/4" 3/8" & 1/2" so I dont have to keep swapping collets.
Give it a try, you can knock one up in a few minutes. It helps to have a bit of marker pen on the outer edge of the ball race so you can see when it makes contact and stops spinning.

Phil

[Jo]

Your tempting me 

Jo

[pgp001]

I have "almost" finished with the mods and additions to my little Boley jig borer now, one of the last jobs was to sort out the main spindle head.
It had a bit of wear in the feed screw, not a lot but enough to niggle me every time I used it.
So I decided to make a new screw and nut, however on examination the bronze nut was perfectly serviceable and it just needed a new screw.
I also decided to try and improve on the design while I was at it, to strip the head apart was a really fiddly job that meant a lot of work every time it needed cleaning and lubricating, so I decided to modify the castings to allow it to run off one end and also gain a bit more travel at both ends as well. Anyone with a Boley or a mk2 BCA will know the headroom under the cutter is a bit limited, so an extra 3/4" or so is quite useful.

Here are a few photo's of the new screw being made.



It is a left hand Acme thread 0.1" pitch.



The keyway being cut with a packing block supporting it from the rear.



Old short and new long screw side by side



The head castings needed some material removed as shown by the markings.





Here the sliding part is set up on the Alexander to put a radiused relief in the back to allow it to go up past the micrometer dial.







The fixed part of the slide was then set up to remove some material from the centre, this allows the bronze nut to travel further within the casting.





Phil