Spot Facing With Slot Drill?

[Dr_GMJNParticipant @dr_gmjn]

Posted by JasonB on 16/05/2020 16:53:19:

Did you definately start with silver steel?

I was just about to edit my post…

The fact is I don’t know for sure. I got a selection of materials when I got my lathe, just to experiment with. The stuff I used was marked silver steel in the tray. It’s the same with the side milling stuff, marked unhardened tool steel.

Before going any further, on Monday I will order some new materials: silver steel bar and mild steel plate (or whatever grade I need to establish whether the machine needs adjusting). I need some mild steel strip anyway for a car project.

Then I will start again with both the side mill test (with a new premium cutter), and start from scratch with the spot facing tool.

I’m using materials that to the best of my knowledge are right, but they could have got mixed up I guess.

[duncan webster 1Participant @duncanwebster1]

After you've hardened it and before tempering try it with an old file. If it skates off it's hard

[Mike PooleParticipant @mikepoole82104]

The spark test can be handy for sorting out materials into rough groups, google will provide plenty of detail on what to look for and how to perform the test.

Mike

[Anonymous]

Posted by Dr_GMJN on 16/05/2020 17:07:21:

The fact is I don’t know for sure.

Some advice:

Recycle all your unknown metal and buy known material from a reputable source – otherwise you're just wasting your, and our, time.

Andrew

[HopperParticipant @hopper]

What rpm did you run that cutter at? You cant use HSS speeds with silver steel. Try taking it nice and slow on that cast iron hard skin. Maybe like 400 rpm or so. Or even less to start with.

Edited By Hopper on 17/05/2020 02:55:03

[Ron LadenParticipant @ronladen17547]

Thought I would have a go and make up a spot facing tool to suit the M4 nuts I have, it turned out ok, though I think I will reduce the diameter as I prefer it a bit tighter to the nut than I have it at the moment.

It was the first time I have hardened any silver steel but it seems to have gone ok, it cuts cast iron quite easily and fairly clean to. I was lazy this morning, I was going to file the teeth but did it all on the lathe and mill in the end.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Ron Laden on 17/05/2020 14:34:10:

[…]
I was lazy this morning, I was going to file the teeth but did it all on the lathe and mill in the end.

.

A brief description of how you went about that would probably be useful to many, Ron

Excellent result, Sir !!

MichaelG.

[Dr_GMJNParticipant @dr_gmjn]

Posted by Hopper on 17/05/2020 02:54:09:

What rpm did you run that cutter at? You cant use HSS speeds with silver steel. Try taking it nice and slow on that cast iron hard skin. Maybe like 400 rpm or so. Or even less to start with.

Edited By Hopper on 17/05/2020 02:55:03

Hopper, to be honest I was running at a lot more than 400rpm. But t's irrelevant; I made a mistake (or at least trusted a years old storage label) and used, I think stainless – it's not magnetic.I should have at least checked before, but lesson learned.

I am ordering some silver steel and a few other bits later today from M-Machine, and will make new storage boxes and mark the pieces with fet tip. I will try again when I get them, and hopefully it will work.

[Dr_GMJNParticipant @dr_gmjn]

Posted by Ron Laden on 17/05/2020 14:34:10:

Thought I would have a go and make up a spot facing tool to suit the M4 nuts I have, it turned out ok, though I think I will reduce the diameter as I prefer it a bit tighter to the nut than I have it at the moment.

It was the first time I have hardened any silver steel but it seems to have gone ok, it cuts cast iron quite easily and fairly clean to. I was lazy this morning, I was going to file the teeth but did it all on the lathe and mill in the end.

Nice work Ron. As I said, I will try again next week. At least I know how to make the tool now!

[Ron LadenParticipant @ronladen17547]

Posted by Michael Gilligan on 17/05/2020 14:46:16:

Posted by Ron Laden on 17/05/2020 14:34:10:

[…]
I was lazy this morning, I was going to file the teeth but did it all on the lathe and mill in the end.

.

A brief description of how you went about that would probably be useful to many, Ron

Excellent result, Sir !!

MichaelG.

Thanks Michael,

I started with a piece of 10mm silver steel bar and turned the 6mm shank and 8mm body as one piece, I then drilled a 4mm hole (M4 clearance) 10mm deep into the body to take the 4mm spigot later. I should say before someone jumps on me I dont use recommended clearance sizes, for me I think the are too big so M4 I use 4.0mm, M6 – 6.00mm, M8 – 8.0mm etc.

Milling the teeth I just picked up on one of Jasons pictures where he showed the tool set up in a Stevensons square collet block at an angle on the mill. I dont have a Stevensons block (yet) so had to come up with something else. I drilled a 6mm hole to accept the shank through a piece of alu round bar and fitted a grub screw to lock the shank. I then squared of the sides of the bar making sure the four faces were 90 degrees to one another (picture below).

With the tool locked into the bar/block and the block mounted in the vice I set up the angle for cutting the teeth. The angle was created simply by positioning the side of block against a piece of flat bar on which I had milled an angle on the end, nothing technical I havnt measured the angle I just went with what I thought looked right for the teeth. I then positioned the vice in Y so the the edge of the cutting tool was at the centre of the tool body, touched off the tool to the top of the body and then took 4 x 0.5mm cuts in X, 2.00mm total which again looked about right. It was then just a case of turning the block through 90 degrees and repeating the same for the othe 3 faces. I then stood the block vertical and "just" skimmed the top of the four teeth to make sure non were sitting proud. Then ten minutes spent with the diamond file I created a shallow rake angle on each tooth.

Then finished with the hardening and fitted the spigot with 638 retainer.

Sorry for the war and peace explanation but its the best way I could explain it.

Ron

[Ketan SwaliParticipant @ketanswali79440]

Posted by Dr_GMJN on 16/05/2020 17:07:21:

Then I will start again with both the side mill test (with a new premium cutter),

Please also check your 'Inbox' at the top of this page, where I have sent you a PM.

Ketan at ARC

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Ron Laden on 17/05/2020 17:07:13:

Sorry for the war and peace explanation but its the best way I could explain it.

Ron

.

Nice description, Ron

… I’m sure it will become a point of reference next time somebody needs ti make one.

MichaelG.

[not done it yetParticipant @notdoneityet]

Don’t do it like that next time, Ron.

Get yourself the Stevenson’s blocks – both square and hex -‘cos they are a real help, with all sorts of jobs.🙂. I got extra nuts for mine as they come in handy if one needs to swap cutting tools (like drilling, threading, counter -boring or -sinking, and chamfering all in the one position. I only have one of the more expensive bearing-type nuts (at the moment) but that is always the favourite as first choice.

[Ron LadenParticipant @ronladen17547]

Yes I do need to get them ordered, ARC do a square and hex as a set.

Wanting to get the tool made I needed something hence the small alu block I made up, it did work well enough though.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Ron Laden on 18/05/2020 05:28:18:

[…]

Wanting to get the tool made I needed something hence the small alu block I made up, it did work well enough though.

.

… and credit to you for that, Ron

MichaelG.

[Alan CharlestonParticipant @alancharleston78882]

Hi Ron,

I'm not clear as to how you milled the teeth. From your picture, I can see that the bottom of the cutter is in the same plane as the angled part of the tooth but the side of the cutter doesn't line up with the part of the tooth which is parallel to the drill. If the teeth were cut as shown, wouldn't you end up with a negative rake? Did you file the side of the tooth after milling to give a neutral rake?

Regards,

Alan

Sorry Ron, I've looked at your post again and I see you say you filed the cutter after hardening to sort the rake out. I initially thought you meant you had filed the top of the teeth to provide clearance after milling the top of the teeth to ensure they were all the same height.

Alan

Edited By Alan Charleston on 18/05/2020 07:30:11

[Dr_GMJNParticipant @dr_gmjn]

Posted by Alan Charleston on 18/05/2020 07:19:23:

Hi Ron,

I'm not clear as to how you milled the teeth. From your picture, I can see that the bottom of the cutter is in the same plane as the angled part of the tooth but the side of the cutter doesn't line up with the part of the tooth which is parallel to the drill. If the teeth were cut as shown, wouldn't you end up with a negative rake? Did you file the side of the tooth after milling to give a neutral rake?

Regards,

Alan

Sorry Ron, I've looked at your post again and I see you say you filed the cutter after hardening to sort the rake out. I initially thought you meant you had filed the top of the teeth to provide clearance after milling the top of the teeth to ensure they were all the same height.

Alan

Edited By Alan Charleston on 18/05/2020 07:30:11

If the cutter moves right to left, and the back of the cutter is on the centreline if the part, wouldn’t it simultaneously form a zero rake tooth face and the angled part of the tooth in front? So in the picture it’s cutting the tooth that’s facing us on the left, and the sloping bit of the tooth in front looks like a horizontal line. Then locally file the ramp just adjacent to the face of the tooth. That’s how I understood it.

Edited By Dr_GMJN on 18/05/2020 08:07:20

[Ron LadenParticipant @ronladen17547]

Posted by Alan Charleston on 18/05/2020 07:19:23:

Hi Ron,

I'm not clear as to how you milled the teeth. From your picture, I can see that the bottom of the cutter is in the same plane as the angled part of the tooth but the side of the cutter doesn't line up with the part of the tooth which is parallel to the drill. If the teeth were cut as shown, wouldn't you end up with a negative rake? Did you file the side of the tooth after milling to give a neutral rake?

Regards,

Alan

Sorry Ron, I've looked at your post again and I see you say you filed the cutter after hardening to sort the rake out. I initially thought you meant you had filed the top of the teeth to provide clearance after milling the top of the teeth to ensure they were all the same height.

Alan

Edited By Alan Charleston on 18/05/2020 07:30:11

Hi Alan,

No it is as you thought, when you turn the block through 90 degrees the cut runs through the previous cut with the edge of the tool creating the face of the tooth which is neutral. In hindsight I probably didn't need to dress the top of the teeth but in doing so it left flat spots on top of the teeth and it was those that I filed a small relief to. So my teeth have a neutral face and a relief on top or bottom if you like.

I don't know if Jason leaves a neutral face but I,m sure he will confirm.

[JasonBModerator @jasonb]

Yes just a zero rake face left by the edge of the tool seems to work OK, you could use a triangular file to add soem positive rake or even use a dovetail type cutter to do the same.

First cut and the edge of the tool forms the first cutting face.

.

Next cut forms the clearance and you get the cutting edge where they meet

[Ron LadenParticipant @ronladen17547]

Thanks for that Jason far better than I was explaning it.

[Dr_GMJNParticipant @dr_gmjn]

And the CAD is a left/right mirror image of Ron's photo presumably?

[JasonBModerator @jasonb]

That's a reverse spot facer for those that don't want to run in reverse

Conventional would end up like this

[John BaronParticipant @johnbaron31275]

Posted by Dr_GMJN on 17/05/2020 16:01:35:

Posted by Hopper on 17/05/2020 02:54:09:

What rpm did you run that cutter at? You cant use HSS speeds with silver steel. Try taking it nice and slow on that cast iron hard skin. Maybe like 400 rpm or so. Or even less to start with.

Edited By Hopper on 17/05/2020 02:55:03

Hopper, to be honest I was running at a lot more than 400rpm. But t's irrelevant; I made a mistake (or at least trusted a years old storage label) and used, I think stainless – it's not magnetic.I should have at least checked before, but lesson learned.

I am ordering some silver steel and a few other bits later today from M-Machine, and will make new storage boxes and mark the pieces with fet tip. I will try again when I get them, and hopefully it will work.

If its silver steel / drill rod, once you have got it to red heat and quenched it it will be glass hard ! If you use it like that without tempering, make sure that you wear safety specs.

[Dr_GMJNParticipant @dr_gmjn]

Posted by JasonB on 18/05/2020 11:16:19:

That's a reverse spot facer for those that don't want to run in reverse

Conventional would end up like this

Yes, that was my understanding – one pass of the cutter right to left forms everything.

I'm going to try that method when I get the steel.

If I make a fixture like Ron's, any tips for marking out the rotation positions on the steel shaft ie 0, 90, 180, 270?

Is there an optimum number of cutting edges to reduce vibration?

Thanks.

[Dr_GMJNParticipant @dr_gmjn]

Posted by John Baron on 18/05/2020 11:26:31:

Posted by Dr_GMJN on 17/05/2020 16:01:35:

Posted by Hopper on 17/05/2020 02:54:09:

What rpm did you run that cutter at? You cant use HSS speeds with silver steel. Try taking it nice and slow on that cast iron hard skin. Maybe like 400 rpm or so. Or even less to start with.

Edited By Hopper on 17/05/2020 02:55:03

Hopper, to be honest I was running at a lot more than 400rpm. But t's irrelevant; I made a mistake (or at least trusted a years old storage label) and used, I think stainless – it's not magnetic.I should have at least checked before, but lesson learned.

I am ordering some silver steel and a few other bits later today from M-Machine, and will make new storage boxes and mark the pieces with fet tip. I will try again when I get them, and hopefully it will work.

If its silver steel / drill rod, once you have got it to red heat and quenched it it will be glass hard ! If you use it like that without tempering, make sure that you wear safety specs.

I was tempering by getting it yellow-ish and re-quenching in brine.

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