Hemingway Knurling Tool

[Mark Elen 1Participant @markelen1]

I’ve gone off at a tangent with my hacksaw build to make another tool for use making the hacksaw. I need a knurling tool, so I thought I would make one.

Now I’ve got the kit and the drawings, I’ve been busy working out sequencing. The first item on the list is the upper and lower arms from 1” x 1/2” BMS.

There are 2 radius cuts to make on the ends of the arms where the wheels fit and I’m planning on milling these out on the rotary table. The only issue is that the centre of the radius is not within the material, so I’ve been busy pondering how to centre these on the table centre. I’ve come up with a plan to make a jig from a piece of 2mm brass that will both identify the centres and space the work up off the table.

Tonight’s embryonic photo of said plate:

Cheers

Mark

[Mark Elen 1Participant @markelen1]

[larry phelan 1Participant @larryphelan1]

My knurling tool was made from "Drawings" on the back of a cornflake box. It,s not pretty [not much of my stuff is ],but ten years down the line,it,s still working.

Take it from me,it,s not Rocket Science,even I could make one,and that,s saying something!

It,s nothing more than two wheels in a frame.

[Mark Elen 1Participant @markelen1]

Hi Larry,

Thanks for your comments. I know, I’m probably going a bit ott, but I’m enjoying the journey and learning a lot on the way.

Today I cracked on with the jig, made a couple of 6mm silver steel pins, drilled and tapped M4 and fixed to the jig with 10mm countersunk screws.

I’ve marked out the centres of the offset radii using the dro.

Cheers

Mark

[lfoggyParticipant @lfoggy]

I made one of these recently. The radii were made by clamping the the two arm to the milling machine table. They were positioned a suitable distance apart and a boring head was used to bore a 'hole' around an imaginary centre located between the parts. This generated the curves. Hard to describe but quite easy to do. Worked very well.

Incidentally, you can buy fine, medium and coarse knurling wheels in the 5/8×3/16×1/4 size from Zoro.co.uk

[Mark Elen 1Participant @markelen1]

Thanks Ifoggy,

Always good to know where to get bits from👍. How did you machine the outside curve on the arms?

I drilled out the 2 arms tonight, and, to my amazement, they both fit on the jig.

Cheers

Mark

[lfoggyParticipant @lfoggy]

I made the outside radii by hand on a linishing machine. This is very quick and gives a perfectly good result for curves that only have to be cosmetically accurate.

I would also recommend hardening the pins on which the knurling wheels run. Otherwise they wear out very quickly.

Edited By lfoggy on 08/12/2018 12:57:54

[thaiguzziParticipant @thaiguzzi]

Touche!

[Mark Elen 1Participant @markelen1]

Thanks Gents👍

I have got all set up on the table and started milling out the ends of the arms:

I’m just nibbling .25mm at a time off as this is the first test of the fixture plate and clamping system.

Cheers

Mark

[Mark Elen 1Participant @markelen1]

Inside done, set up and milled the outside, I ended up taking 1mm at a time, the table seems secure, although, the backlash in the RT makes climb milling ‘interesting’. I ended up taking .1 mm climb with the table locks nipped down to finish off and it worked out ok.

Cheers

Mark

[lfoggyParticipant @lfoggy]

Very nicely done.

That's an interesting clamping plate you have mounted to your rotary table.

[Mark Elen 1Participant @markelen1]

Thanks lfoggy,

The sub-table is loosely based on Chris’ at Clickspring, see here:**LINK**

There are some build photos of my version of the sub-table on my hacksaw thread, starting here: **LINK**

As soon as I saw Chris using his, I knew it would get a lot of use if I made one.

Cheers

Mark

[not done it yetParticipant @notdoneityet]

While the internal radius is a ’must-have’ (or at least there must be clearance for larger diameter workpieces) the outer seems to be more weight-saving or aethsetic – or perhaps seeing the wheels allows easier lubrication while cutting?

[Mark Elen 1Participant @markelen1]

Hi NDIY,

I think you’re right there.

I got on this morning, made the other half and then got set back up in the vice to machine out the pivot ends. As they are both the same, I set both up together in the vice, used a piece of 6mm silver steel in the collet Chuck to register the pieces and confirm that they lined up correctly.

Still got a bit more to go with the boring head to get to dimension.

Cheers

Mark

[John BaronParticipant @johnbaron31275]

Hi Mark,

I would have glued both pieces together and put them in the four jaw on the lathe, drilled to remove the waste and then bored both holes to size.

However its an interesting technique that you have used. I'm watching with interest.

[DalboyParticipant @dalboy]

Thank you for showing the work in progress for me it is interesting how people get around certain things even if it is for something simple.

[Mark Elen 1Participant @markelen1]

Hi Gents,

I find lots of inspiration from other people’s build threads and how they find ways of working.

I got the bore to final dimensions this afternoon, followed with a 14mm slot cutter, then I tried out a 10mm roughing end mill. Wow, that thing eats through it. I probably went a bit far with the rougher, I only left myself .1mm for a climb cut to finish with a standard end mill. There are still signs of the rougher in the finish. Never mind, every day is a school day.😂

They still look a bit funny because one piece was about 2mm longer than the other before I started on them. I now need to set up the rotary table again to mill off the ends.

Cheers

Mark

[lfoggyParticipant @lfoggy]

That fixture plate is a great idea. May make one myself. You need a big bit of metal to make this though. Why did you choose aluminum instead of steel? Lighter and easier to machine but may deform under clamping pressure? Clcikspring has used brass which seems extravagant !

[Mark Elen 1Participant @markelen1]

Hi lfoggy,

To be honest, I used aluminium because I didn’t want to have to drill and tap 60 odd holes M8 in steel. My plate is 40mm thick, so I have blind tapped to 30mm. I was concerned about stripping threads, but it seems fairly durable, I’m sure time will tell.

Chris used aluminium, because apparently, steel is hard to come by in Australia. If I was to make one in steel, it wouldn’t be 40mm thick, because, that plate of mine is heavy enough.

I have done similar to Chris and machined a register in the middle and drilled and tapped the MT2 arbour that fits into the table M6.

I expect that most of the time, in use, there will be a central hole that will be machined around, so it will do the majority of the clamping and the table will be more for location.

Cheers

Mark

[lfoggyParticipant @lfoggy]

Yes, aluminium probably a more practical choice. Where did you get the piece of metal from?

[Mark Elen 1Participant @markelen1]

Hi lfoggy,

I got it from someone on e-bay. I was expecting a ‘rough sawn’ blank, to be honest, it didn’t take much work to finish it. The time consuming part was the setting up, drilling and tapping etc.

Cheers

Mark

[Mark Elen 1Participant @markelen1]

After the success with boring the 5/8” hole between the 2 arms, today I decided to use a sacrificial piece of steel to bore the 5/8” hole on the top arm. I made up a 5/8” brass plug to gauge size. I really need to get a set of bore gauges.

I also got the bottom arm drilled and reamed out 1/4”

After using the bore gauge, i used part of it to make a centre for my fixture plate, just a plain centre, drilled and reamed 6mm for use on the next operation, rounding off the ends of the arms.

Cheers

Mark

[Mark Elen 1Participant @markelen1]

I made a start on the ends tonight, changed the vice out for the rotary table… again… and got set up. I’m going to take it down to .25mm with the rougher then take the last bit with an end mill and see how that works out.

Cheers

Mark

Edited By Mark Elen 1 on 10/12/2018 21:56:41

[Mark Elen 1Participant @markelen1]

Tonight I’ve got all of the radiused ends done on both arms.

Here is my method of centering parts. I turned up a central spigot, as the locating holes in the arms were 6mm, it’s really just a 20mm extra thick washer reamed 6mm in the centre. I also turned up a 6mm silver steel rod with a point.

With the part free to move and the pointer chucked up in a collet, the pointer was fed through and located in the spigot, then the arm was clamped down and a 6mm screw is fed through the centre of the table and threads into the MT2 stub arbour that the sub-plate locates on.

It all worked a treat and I’m happy with the results.

Cheers

Mark

[Ian Skeldon 2Participant @ianskeldon2]

Nice work mate.

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