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Hemingway Knurling Tool

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Mark Elen 105/12/2018 22:36:25
107 forum posts
179 photos

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:

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Cheers

Mark

larry phelan 106/12/2018 17:16:11
433 forum posts
11 photos

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 107/12/2018 19:11:20
107 forum posts
179 photos

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.

db2e156f-8d55-4a79-9d7b-808cb92d02b7.jpeg

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Cheers

Mark

lfoggy07/12/2018 20:08:13
53 forum posts
5 photos

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 5/8x3/16x1/4 size from Zoro.co.uk

Mark Elen 107/12/2018 22:32:38
107 forum posts
179 photos

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.

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Cheers

Mark

lfoggy08/12/2018 12:46:08
53 forum posts
5 photos

20181208_095448.jpg

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

thaiguzzi08/12/2018 15:08:39
avatar
530 forum posts
108 photos

phone photos to sept 2017 545.jpgphone photos to sept 2017 542.jpg

Touche!

Mark Elen 108/12/2018 16:44:02
107 forum posts
179 photos

Thanks Gents👍

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

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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 108/12/2018 21:02:00
107 forum posts
179 photos

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.

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Cheers

Mark

lfoggy08/12/2018 22:18:12
53 forum posts
5 photos

Very nicely done.

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

Mark Elen 109/12/2018 00:03:29
107 forum posts
179 photos

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 yet09/12/2018 10:33:33
3007 forum posts
11 photos

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 109/12/2018 11:22:48
107 forum posts
179 photos

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.

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

Cheers

Mark

John Baron09/12/2018 12:17:07
avatar
77 forum posts
13 photos

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.

Derek Lane 209/12/2018 13:09:52
avatar
189 forum posts
48 photos

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 109/12/2018 15:51:59
107 forum posts
179 photos

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.😂

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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

lfoggy09/12/2018 16:34:50
53 forum posts
5 photos

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 109/12/2018 17:00:31
107 forum posts
179 photos

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

lfoggy09/12/2018 20:46:47
53 forum posts
5 photos

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

Mark Elen 109/12/2018 21:11:30
107 forum posts
179 photos

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

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