Practice facing

This topic has 23 replies, 10 voices, and was last updated 4 January 2019 at 19:43 by Niels Abildgaard.

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3 January 2019 at 23:12 #389246
Adrian Harrison
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@adrianharrison27934
I spent a good 4 hours today just going through my HSS tooling that came with my lathe to see what works for facing of, i did manage to get a better finish at the end but I'm wondering if its possible to do better..
here two pictures of the setup that i found the best and the tool that i used, please any input that would help let me know

Adrian
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3 January 2019 at 23:12 #9467
Adrian Harrison
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@adrianharrison27934
3 January 2019 at 23:13 #389248
Adrian Harrison
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@adrianharrison27934
and yes my poor lathe does need a good clean and paint which I will do this summer when the weather is warmer
3 January 2019 at 23:26 #389251
Former Member
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@formermember32069
[This posting has been removed]
4 January 2019 at 03:40 #389261
Adrian Harrison
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@adrianharrison27934
Posted by Barrie Lever on 03/01/2019 23:26:46:

Adrian

That looks like a brazed tip carbide tool not HSS, nothing wrong with that though.

What is the material?

Unless there is something horribly wrong with the lathe I am fairly sure you will get a better finish than that that.

Are you in Canada?

Regards

Barrie

Hi Barrie yes I am in Canada and its cold rolled steel so probably not the best metal to use
4 January 2019 at 05:19 #389265
Thor 🇳🇴
Participant
@thor
Hi Adrian,

Brazed carbide tipped tools may need to be sharpened to get a good finish, you can use a "green wheel" to grind the cutting edges and then I use a diamond hone. This improved my brazed carbide tipped tools. If you have some HSS tools they can be sharpened with an ordinary wheel on a bench grinder and honed afterwards. As you say, cold rolled steel may not be the best metal to turn, try and get some freecutting steel. When facing you should ideally increase the speed as the tool approaches the centre of the work, so if you have a DC motor or a 3-phase motor with inverter just adjust the speed.

Thor
4 January 2019 at 05:52 #389267
Adrian Harrison
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@adrianharrison27934
Posted by Thor on 04/01/2019 05:19:46:

Hi Adrian,

Brazed carbide tipped tools may need to be sharpened to get a good finish, you can use a "green wheel" to grind the cutting edges and then I use a diamond hone. This improved my brazed carbide tipped tools. If you have some HSS tools they can be sharpened with an ordinary wheel on a bench grinder and honed afterwards. As you say, cold rolled steel may not be the best metal to turn, try and get some freecutting steel. When facing you should ideally increase the speed as the tool approaches the centre of the work, so if you have a DC motor or a 3-phase motor with inverter just adjust the speed.

Thor

Hi Thor.. I do have a diamond hone that i have been using to sharpen HSS tooling that came with my lathe but did not sharpen the carbide one i tried. it didi give me the best finish today as it was
i have an older 1924 lathe with on and off switch for the motor and thats all the motor has
4 January 2019 at 07:20 #389272
Hopper
Participant
@hopper
It might help a little bit if you slide the tool back into the toolpost a bit. More overhang = more flex = poorer finish.

I've found my old Drummond works best with HSS tooling sharpened to a very sharp edge with a lot of top rake on the tool. Ie, "knife tool". Never had much luck with carbide on the Drummond. Seems to work better on the Myford 7 with stouter headstock bearings and spindle.
4 January 2019 at 08:43 #389280
not done it yet
Participant
@notdoneityet
As Hopper. That tool may be rigid but any excess overhang presents a larger leverage on the rest of the machine.

The ideal cutting point would be directly above the centre of the carriage and bed – but not really achievable. As close as possible to the ideal is the best we can do and the further away is “less betterer”

The lighter the lathe, the more important these things become. With more-worn lathe parts, little things become even more important….
4 January 2019 at 08:51 #389281
Hopper
Participant
@hopper
Yes, it looks like you could move the topslide back over the cross slide a little bit more too. And ensure the topslide is retracted to where it's on solid base wherever possible. Every little bit helps on these old machiens. Keep the cutting edge of the tool just ahead of the leading edge of the cross slide so the cross slide does not hit the chuck.

Edited By Hopper on 04/01/2019 08:52:55
4 January 2019 at 10:10 #389289
roy entwistle
Participant
@royentwistle24699
Try starting in the centre and work out

Roy
4 January 2019 at 14:41 #389320
colin hawes
Participant
@colinhawes85982
Keep HSS tools very sharp and with plenty of clearance rake at all cutting edges. I find that industrial recommended rake is too little for the sort of work we usually do. Colin
4 January 2019 at 16:18 #389331
Adrian Harrison
Participant
@adrianharrison27934
would this be classed as a knife edge? I did try a google but did not really find any info

so i should keep the top slide over the cross slide as possible and keep the tooling as short as possible..
i had read that HSS tooling is best for the speeds of this lathe and i will get a bench grinder fro home as the only one i have access to is at work..
4 January 2019 at 16:25 #389333
Adrian Harrison
Participant
@adrianharrison27934
Posted by Hopper on 04/01/2019 08:51:30:

Keep the cutting edge of the tool just ahead of the leading edge of the cross slide so the cross slide does not hit the chuck.

Edited By Hopper on 04/01/2019 08:52:55

so the cutting edge is just sticking out over the edge? i was wondering if i should turn too holder 90 degree to face the part I'm facing off
4 January 2019 at 16:27 #389334
Adrian Harrison
Participant
@adrianharrison27934
Posted by roy entwistle on 04/01/2019 10:10:28:

Try starting in the centre and work out

Roy

I was thinking about this as i think it may put less side loading on the workpice
4 January 2019 at 16:47 #389338
Niels Abildgaard
Participant
@nielsabildgaard33719
Your tool post system is too soft and cutting edge probably not very sharp.

See what can be done on a small lathe(Boxford) .

A picture of lathe will be helpfull.

https://www.youtube.com/watch?v=DeFLeNPhqDY

Edited By Niels Abildgaard on 04/01/2019 16:48:27

Edited By Niels Abildgaard on 04/01/2019 16:49:50
4 January 2019 at 17:22 #389344
Adrian Harrison
Participant
@adrianharrison27934
how do you mean too soft?
4 January 2019 at 17:24 #389345
Adrian Harrison
Participant
@adrianharrison27934
that lathe in the youtube clip looks amazing
4 January 2019 at 17:54 #389355
Tim Stevens
Participant
@timstevens64731
Adrian – if you look closely at your tool clip you can see a bright line where the edges meet. This is where the light is reflecting off a rounded surface, ie not a sharp edge. Any tool which shows this effect on the business edges could benefit from sharpening.

Cheers, Tim
4 January 2019 at 18:12 #389358
Adrian Harrison
Participant
@adrianharrison27934
Posted by Tim Stevens on 04/01/2019 17:54:26:

Adrian – if you look closely at your tool clip you can see a bright line where the edges meet. This is where the light is reflecting off a rounded surface, ie not a sharp edge. Any tool which shows this effect on the business edges could benefit from sharpening.

Cheers, Tim

do you mean all the lines on he face?
4 January 2019 at 18:22 #389359
Tim Stevens
Participant
@timstevens64731
No, Adrian, the shot of the tool on its own, where the text begins 'would this be classed as a knife edge'

The edges I refer to are really the surfaces of the top face and the ground side you can see. For some of the edge there is no reflected light, but this is behind the cutting end, and shows what a sharp edge should look like.

Hope this helps

Tim
4 January 2019 at 18:31 #389360
Adrian Harrison
Participant
@adrianharrison27934
Right I see what you mean.. I have not used this tool yet but I will make sure i sharpen it before i do

Thanks for the input
4 January 2019 at 19:03 #389364
John Reese
Participant
@johnreese12848
Here is a guide to tool angles. Only the right hand tool is shown.

https://littlemachineshop.com/reference/rakerelief.php

The illustration shows what the tip should look like. It will work for turning or facing.

Other sources for tool geometry may be based on the use of a lantern toolpost. The toolholders for that toolpost have a 15* back rake built into the holder. Any of the assortment of HSS bits in your collection without back rake ground into the tool were likely designed for use in a holder for the lantern toolpost. Their geometry will be wrong if the bit is held horizontal. Sort them out and regrind them to work with your tool post.
4 January 2019 at 19:43 #389377
Niels Abildgaard
Participant
@nielsabildgaard33719
Posted by Adrian Harrison on 04/01/2019 17:22:15:

how do you mean too soft?

A somewhat more rigid solution is described here

https://www.model-engineer.co.uk/forums/postings.asp?th=139294&p=2

Edited By Niels Abildgaard on 04/01/2019 19:43:52
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