Lathe tools

[rosinante]

Got a lathe as per earlier post, now looking at new cutting tools for it, it is a grayson lathe 3.5 in center ht Q, what size and sort of tools should I get,budget limited of course,not so bothered about quick change etc, if they are all same shank size will
cutting height be the same?
Cheers
Chris

 

[rikrobson]

There are 3 basic types of cutting tools.

1: High Speed Steel. These you gring yourself from pieces of HSS. the centre hight will depend on how you hace ground the cutting edge and will tend to be a fair way below the top of the tool. Therefore the cutting hight will differ.

2: Brazed Tungsten Carbide tiped. This is a steel tool with a TC tip brazed onto the shaft. These will tend to have the same cutting hight depending on how they were originally made.

3. TCT inserts. these have rhomboid or triangular TC tips that able to be swaped out. these will have the same cutting hight.

the hight will depend on the shank of the tooling, therefor a 1/2" tool will have a different hight to a 3/8" tool.

You should have some shims to pach underneath the tool to get it to the correct height.

A Quick change tool post will have a method to hage the height easily without shimming. usually a screw or knurlled thumb wheel.

The next best is a 4 way post where you can keep 4 tools in the post at one time and rotate the post.

If its just for hobby use the few minutes it takes to change and setup a tool, should not be a big problem. It is only where Time is money that the time taked to change tools becomes a problem.
Saying that though a QC toolpost is the way to go

 

[rosinante]

Thanks for quick reply, which tools and post would you recommend for my lathe,a Grayson which I believe to be similar to an early myford but don't quote me on that, Cheers
Chris

 

[rikrobson]

you should be fine with HHS tooling. Get a bench grinder if you havent already.

This will be the cheapest way.

I got a set of inserts for my boxford the other day and they do cut better, but i've used HSS for a long time. Onee drawback with TCT tooing is that you cant shape it. the insertsare the shapoe they are, but the hss toos can be easily shaped on a grinder.

 

[MattF]

Another preference for HSS here. That's what I always used with the Warwick, (pretty much the exact same lathe as the Grayson), and never had any issues using it. The lathe itself was always the weak point, (it had some wear), never the tooling. You can also get the J&S, Armstrong etc. holders for using 1/4" tool steel, so that saves a bit on the cost of buying 1/2"> steel.

 

[T0rnado69]

when i brought my lathe, i brought no2.

Brazed Tungsten Carbide tiped tools.

i didn't know any better back then.

but after using them for a while,
it soon got a pain in the you know what.
having to get them sharpened and waiting a week to collect them.

so ive changed to no 3. TCT inserts.

the cost of 1 insert is about the same for getting one brazed one sharpened.
you then got the cost of fuel taking and collecting it.
ohhh and the insert can be turned round to use the otherside..
so really its cheaper for 1 insert then getting the brazed tct sharpened.

i find inserts much better, quick to change
no waiting for tools to be sharpened.

i will get into trying HSS..
as stated you can grind it to any shaped tool you need.
easy to resharpen yourself.

 

[brightspark]

90 percent of cutting can be done with hss tipped tools sharpened on your grinder

 

[Pete.]

Got a lathe as per earlier post, now looking at new cutting tools for it, it is a grayson lathe 3.5 in center ht Q, what size and sort of tools should I get,budget limited of course,not so bothered about quick change etc, if they are all same shank size will
cutting height be the same?
Cheers
Chris

1/3" or 3/8" shank tool blanks will be more than adequate for your lathe Chris. If you have a bench grinder with a dressing tool then grind your own but I have also taken now to finishing the edges with a diamond lapidary disc and it gets instant sharp high-polished cutting edges.

For a small lathe, especially when cutting aluminium, a tool with a high top-rake will cut easily and not make the lathe motor struggle.

 

[addjunkie]

Plenty articles on line about grinding up hss tools to the correct shape and rake angles etc. Or any basic lathe book will tell you. I quite often reference a text book from my apprentice ship for such things, had it 35 years, glad i kept it really.

Im a fan of hss too, though do use tipped tools too. but for not a lot of money you can buy a set of tct tipped brazed on tools, not the best and half you probably wont use, but will get you going.
http://www.ebay.co.uk/itm/SET-OF-38...168564?hash=item5683aa6074:g:EOgAAOSwoBtW6S6L

 

[MCKDAVID]

for sharpening tips, look up tubalcain or it's maybe under mrpete, on youtube. He does a series of videos on how to cut them using simplistic models and explains all the cutting angles rake angles chip clearance etc. Really good stuff.

would find a link or two for you, but the works blocks youtube access..

 

[MattF]

1/3" or 3/8" shank tool blanks will be more than adequate for your lathe Chris. If you have a bench grinder with a dressing tool then grind your own but I have also taken now to finishing the edges with a diamond lapidary disc and it gets instant sharp high-polished cutting edges.

Is that a disc you have on your bench grinder? Any link/photo for that type of disc? I tend to finish my edges on the oilstone. Low tech, but works for me. Occasionally give the tool a quick tickle on there to freshen the edge up too.

 

[MattF]

Plenty articles on line about grinding up hss tools to the correct shape and rake angles etc. Or any basic lathe book will tell you. I quite often reference a text book from my apprentice ship for such things, had it 35 years, glad i kept it really.

The older books tend to excel for that type of information. When it comes to cutting tools, they cover just about every type, sprung, straight, brazed tip, form etc., tell how to braze tips to steel shanks etc. Not sure how indepth newer books go in that area?

 

[Wedg1e]

Not sure if it's been mentioned but if you se the 'green grit' type of grinding wheel you can resharpen the brazed carbide tools yourself. Cost about £11 for a 6" disc last tiem I bought one, cheaper than buying multiple tools. Could probably reshape the indexable type tips too but what I tend to find is not so much that they go blunt as that they chip, so reshaping them would need tool height etc. altering to suit.

 

[Pete.]

Using a green wheel on carbide tooling is like trying to make fine furniture with a chainsaw. There's no good reason to do it nowadays with diamond abrasives being so affordable and abundant.

 

[ukracer]

1/3" or 3/8" shank tool blanks will be more than adequate for your lathe Chris. If you have a bench grinder with a dressing tool then grind your own but I have also taken now to finishing the edges with a diamond lapidary disc and it gets instant sharp high-polished cutting edges.

For a small lathe, especially when cutting aluminium, a tool with a high top-rake will cut easily and not make the lathe motor struggle.

When you say "high top rake" could you expand a little?
Close to "flat" ?

 

[Pete.]

Is that a disc you have on your bench grinder? Any link/photo for that type of disc? I tend to finish my edges on the oilstone. Low tech, but works for me. Occasionally give the tool a quick tickle on there to freshen the edge up too.

Yes I'll take a pic of it tomorrow. I bought the discs for sharpening carbide scrapers but they also do a great job on lathe tools.

When you say "high top rake" could you expand a little?
Close to "flat" ?

Grind the top of the tool at a sharp angle down away from the edge, to form a more knife-blade cutting edge. It will slice through softer materials instead of brute forcing the material away. The results will surprise you when you first do it.

 

[ukracer]

but I have also taken now to finishing the edges with a diamond lapidary disc and it gets instant sharp .

What grit mate. I see a few 6 inch ones on ebay but all different grits.

 

[Pete.]

This is the type of wheel I use. I've always had good service from this particular vendor. Can't remember the exact grits I bought but I think it was 1200 and 2000 which are very fine for honing scrapers. I also have 600 grit cup wheels for shaping stuff.



http://r.ebay.com/YFiCMT

EDIT, just checked it was grit 1200 and 3000. 3000 is very fine for mirror finish. I made an aluminium backing plate for mine and just bolt the diamond discs to it, in fact I bolt them both to it and just swap them over depending on what grit I use.

You have to remember this is for honing the edges only. If you try to grind a tool with these discs you'll wreck them right away.

 

[rosinante]

Well chaps thanks for all your replies,further digging in the box of bits that came with the lathe there are several bits of 1/2 ins hss tools,these have been extensively ground to make them usable, as Pete sez 1/ 4. 3/8 is the max tool size, after lots of pondering Ihave come to think that a quick change tool post isn't what I want more a quick means of shimming ,folding wedges perhaps.
The toolpost I have isn't so much a post more a clamp directly on to the top slide ,any post fitted would have a thin bottom plate in order to allow any tool to be at centre height,have seen 1/4 hss blanks on the bay so ordering some and will progress from there,
Chris

 

[ukracer]

This is the type of wheel I use. I've always had good service from this particular vendor. Can't remember the exact grits I bought but I think it was 1200 and 2000 which are very fine for honing scrapers. I also have 600 grit cup wheels for shaping stuff.



http://r.ebay.com/YFiCMT
http://r.ebay.com/YFiCMT
EDIT, just checked it was grit 1200 and 3000. 3000 is very fine for mirror finish. I made an aluminium backing plate for mine and just bolt the diamond discs to it, in fact I bolt them both to it and just swap them over depending on what grit I use.

You have to remember this is for honing the edges only. If you try to grind a tool with these discs you'll wreck them right away.

Lot cheaper than the
Ones I found.