Author Topic: Shaper Tool Holder - Armstrong Derivative  (Read 413 times)

Offline Joco

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Shaper Tool Holder - Armstrong Derivative
« on: February 17, 2021, 09:41:06 PM »
After getting the little Alba 1A spruced up and working I decided to have a crack at making a tool holder that is based on the Armstong style.  To be clear this is NOT my design.  I have included the pic of the plan for reference which I believe to be in the public domain (i.e. not sold). From memory I found this on the yahoo metal shaper group file section.  It is also referenced at:  https://www.circuitousroot.com/artifice/machine-shop/shaper/literature/index.html

Anyway, this is a record of my build of this tool.   I'm making it from the stock I have on hand, all construction grade mild steel.
Bar/handle - (WxTxL) 25x15x150mm
Head - 30mm OD, 28mm height
M16 bolt and jam nut

I had some fun in the shaper and brought the bar to size from 40mm wide bar stock. I was using a tool made from 12mm sq HSS but with a rather small radius.  On this gummy steel it was probably too small a radius to get a nice finish.

Head as brought to size in the lathe and left solid at this point.  This was done as I did not want to deal with the hole for the M16 bolt to warp post welding.

Head and shaft are TIG welded together.  Clamped to welding table, tacked in four positions then two passes per side.  About 1.5mm filler wire on pass one to really get into the curve then a ~3mm wire to flood out a wider fillet abd being the weld up to the level of the shaft.

After all cooled off the head was chucked up in a 3-jaw in the lathe (with care taken to ensure the shaft would clear everything).  400 rpm was max before bad vibration would set in with the out of balance piece.  The head was drilled and bored to 15.8mm.  This resulting in a rather nice snooth fit from the M16 bolt.

Then off to the mill and set up for the castillians to be made.  Used a parallel wedged into a T slot to act as the reference.  Setup #1 just had the tool shaft against the parallel and clamped down.  Then used a DTI to centre up the mill on the hole in the tool head.  Got that to under 0.01mm.  Used a 6mm end mill to create the 1/4" slots. Thank goodness for a DRO.  Makes life so much easier.

Then on to setup #2 (see pic). Same DTI process to centre up and cut the 45 degree angle slots.

See pic #2 for the results.

Setup/pic #3 used a V block to hold the M16 bolt to drill a 9mm hole to act as the trap for the 1/4" HSS tool bits.  Using a bit of good old math to calculate the diagnonal of a 1/4" square were S is a side you get sqr(S^2 + S^2) which in mm ends up being sqr(2 * 6.35^2) = 8.98mm.  So drilled a hole to 8.7mm (using 11/32 drill) and reamed to 9mm.  Result is a very nice sliding fit on the 1/4" HSS bits I have.

See pics #4, #5, #6 for the results.  All in all not bad.

The shaft has been made nice and long so that the slotting attachement can have the clapper locked through a little attachement to the handle.  More posts to come on both of these parts.

Cheers - J.
James
Wellington - NZ

Offline Steamer5

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Re: Shaper Tool Holder - Armstrong Derivative
« Reply #1 on: February 18, 2021, 05:23:57 AM »
Hi James,
 Looks good!
I let Dad know about this, pretty sure he was looking for one of these.

Cheers Kerrin
Get excited and make something!

Offline Joco

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Re: Shaper Tool Holder - Armstrong Derivative
« Reply #2 on: February 18, 2021, 08:20:24 AM »
Cheers Kerrin.   Now on to the slotting attachment.  Pretty self explanitary from the plans.

Nice long M16 bolt (150mm long from memory).  Made the two holes 85mm between centres and turned down the bolt head to give a little extra length for the tool bit clamp screw to go into. Said clamping screw is M6.

The 11/32" hole that is "supposed" to be a light interference fit on the key stock that locks the shaft in the holder did not turn out that way.  Not too sure why.

The pics show the results with a bit of 1/4" HSS I had lying about inserted.

Cheers - J.
James
Wellington - NZ

Offline pgp001

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Re: Shaper Tool Holder - Armstrong Derivative
« Reply #3 on: February 18, 2021, 09:02:32 AM »
I tried a similar slotting tool holder but found it to be not rigid enough, it would tend to spring quite a bit and dig in if you were not really careful.

My solution was to make a simple one piece tool bar that goes in place of the lantern toolpost.

In the photo it is shown cutting on the forward stroke, but I have found it to be even better if the tool bit is reversed so it cuts on the backwards stroke then it has even less tendancy to pull into the work, the clapper box is also locked in position so it is solid.

This has the added advantage of taking up much less head room on the machine so larger work can be held in the vice or on an angle plate.

Phil

« Last Edit: February 18, 2021, 09:05:39 AM by pgp001 »

Offline Joco

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Re: Shaper Tool Holder - Armstrong Derivative
« Reply #4 on: February 18, 2021, 09:37:38 AM »
Thanks Phil.  I have been wondering about the potential for spring.  Given the bolt is high tensile I have "hoped" that might help. Time will tell.

I looked into the lantern post replacement path but my clapper box does not have a way to lock it closed and I have been loathed to start drilling into things.  Thus this style was seen as a path worth trying.  Nothing ventured nothing gained, as they say.   BUT if I suffer the dreaded spring to a level it causes real issues then I might have to think harder about putting new holes into the head/clapper, or come up with some other system to lock it down.

I have read some suggestion that having the tool bit facing up and cutting up into the work could work as the cutting forces will push the clapper closed on the forward stroke.  Not soo sure if the behaviour on the reverse stroke will be ok.  Given the back rake on the tool bit it should slide back ok.

Cheers - J.
James
Wellington - NZ

Offline pgp001

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Re: Shaper Tool Holder - Armstrong Derivative
« Reply #5 on: February 18, 2021, 10:17:27 AM »
One way to think about spring in the tool, is to liken it to a walking stick  :D

If you press too hard on your walking stick it is in compression and will try to bend.
If you hook your walking stick over a tree branch and start swinging off it, it is now in tension and it will try to straighten out.

The same thing happens with your tooling, push it into the work and it tries to compress and bend, pull it through the work and it does the opposite.
That is why industrial broaches are always pulled through the work.

Phil

Offline Steamer5

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Re: Shaper Tool Holder - Armstrong Derivative
« Reply #6 on: February 21, 2021, 07:32:27 AM »
Hi James,
 Dad says Thankyou for the drawing!
Iíve suggested that we get the holder watercut to save him some work.......heís thinking about it, no rush,!

Cheers Kerrin
Get excited and make something!

Offline Joco

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Re: Shaper Tool Holder - Armstrong Derivative
« Reply #7 on: February 22, 2021, 01:29:31 AM »
Been working on a little clapper clamping block for this tool holder.   I don't have any way to lock the clapper without taking to it with a drill press, which I am not to keen on. So with this Armstrong style tool I deliberately made the shaft long enough that when using the slotting bar I could put a block on the handle and have it wedged against the tool head to stop the clapper from swinging.

Have a look at the pics.  This isn't a new concept as I have seen similar ideas on youtube and in old shaper texts.

Pic 1:  Gratuitous shaper action.  This slot is 25.5mm wide and 16mm down.  From memory the stroke was about 1.5" so pretty sure the block is 25-28mm in the stroke direction.  I had to make a left and right tool and a 60 degree round nose tool to allow me to get down and go left and right.  It was great practice and I learned a lot about the machines limits and the behaviour of different grinds.  However it was definately a reality check as to why milling machines replaced shapers.  A bigger machine probably would have been faster but compared to my Dah Lih mill where I could have run a 20mm roughing mill right through this with coolant in a single pass then cleaned it with a finsihing mill to size in about 15mins or less the shaper took many orders of magnitude longer.

Pic 2 and 3:  Slot done and shaft of tool holder tested, very nice slide fit.

Pic 4 and 5: Showing the clamping block in place.  M8 bolt 30mm long on the back. Faced to have a nice smooth surface to push against either the bolt it is currently against or on to the swivel head.  The M6 bolt on the front that locks the block in place on the shaft head is over length.  Its 20mm and needs to be 10mm.  I am also still on the fence of using that or an M6 or M8 cap screw. The head of the M8 in particular is nice and chunky and easy to grip and snug up with just your fingers.

The block dimensions are going to be need to be specific to your machines sizes and how large you make the shaft.  On this one I made the thin parts 6mm to have good strength but not be too chunky. The thick part at the back is about 20mm or so.

But hopefully you can see that with this block in place the clapper isn't going anywhere which is exactly what you want when slotting, according to the books.  :-)

Cheer - J.
James
Wellington - NZ

Offline pgp001

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Re: Shaper Tool Holder - Armstrong Derivative
« Reply #8 on: February 22, 2021, 07:05:59 AM »
That's a neat and simple solution  :ThumbsUp:

Phil