HSS or Carbide?

Hi All...

I've started to use dad-in-law's 1948 Myford "M" and I'm wondering there would be any advantage in getting some brazed carbide or indexable tools or just stick with the couple of dozen HSS tools and blanks that I already have (6mm and 8mm).

I've never ground lathe tools before but there's plenty of advice here and elsewhere so I'm pretty confident I can learn.

On another tack, has anybody any idea where I can find a lantern tool holder to replace the Norman that's on the lathe?

Cheers

Malc

Hi Malc,

Depending on what you are planning to make, I'd be inclined to stick with HSS tooling if I were you.

I bought a few brazed carbide tools when I started and they now stay in a box apart from the odd times when I want to machine hardened steel or for roughing cast iron or hot rolled when one right hand knife tool does pretty much all I need.

I'd also stick with your Norman toolholder unless you fancy upgrading to a Dickson QCTP perhaps.

HTH

Jon

Unless you are planning to machine hardened steel, stick with HSS.

Your M type Myford probably does not have high enough speeds for Carbide tools to make Carbide work effectively, also it is unlikely to be sufficiently rigid to withstand the heavy loads that you may be tempted to apply with Carbide tooling.

With regard to tool holding; a fourway toolpost will change tools as fast as a QCT, (Not my opinion; this was stated in an article fairly recently in M.E.W.) unless you are planning to use a large variety of tools. Also QCT holders add up the cost, and need space to store.

If possible, do make up a back toolpost, and use this for the parting tool. If it is multi position type, you can mount a front chamfer tool, and posibly a back chamfer tool, for use in conjunction with the parting tool.

Time spent making a Tool Centre Height Setting Gauge will be well spent. Ultimately it will save time, and avoid the pip that results from an off centre tool, not to mention improving the cutting action of the tool.

Too high, (above centre) will rub rather than cut cleanly; too low (below centre) will result in an excessive clearance angle, and less than optimal cutting.

Hope that this helps.

Howard

HSS will likely be fine for most jobs but you may need carbide at some point for some tougher materials. Most of my turning is done with a Tangential tool as it's quick and easy to grind but I have some insert tooling for the odd job. I'm really not a fan of brazed myself.

Also you need a green wheel to properly sharpen carbide.

The shear angle (which I won't go into) is necessarily much more shallow on brittle carbide which pushes up the cutting forces. Not great for delicate little jobs. It's not uncommon to find negative rake angles on indexing tool holders.

Cheap Chinese braised carbide is not of a great grade either.

What I have found is the positive rake ground carbide inserts for Aluminium works very well on steel with my myford lathe. I just do not face across the centre on steel with them. I normally if the part allows put a small centre spot to take away the very center point. I use the TNMG 16mm ground Ali inserts, there is anew one out that is coated for stainless steel, looks similar to the Ali one but instead of being just shiny is a purple brown colour. The local rep call them the wonder insert. They are just the nuts at the moment, and he sells them as singles for the hobby market. I have the 0.4mm radius and the 0.2mm radius. I use the 0.2mm rad insert the most. Unless you do something stupid, they last a long time on mild steel and low tensile. The harder the steel the shorter the life of course. The 6 cutting edges make them cheap per edge compared to the dcmt or ccmt geometry inserts.

I used to have hss all the time.But am a convert to the insert tools on a hobby lathe. Hss is in it's own for 1 off special shapes or low run form tools so still has it's place.

This is a link to his site to give you an idea.

http://www.carbidenz.co.nz/store/index.php?dispatch=products.view&product_id=2194

Neil

Hi Malcolm & all.

When I got back into turning and machining after many year away, I decide I didn't want to spent my time grinding tools up especially parting off tools! So I went for carbide inserts. I quickly found that they are a bit 'precious' with their handling. Just one touch can chip the insert making it useless I known you can turn it round to another cutting edge but you don't want to do that too many times at about £2 plus a time! So it was back to HSS - more forgiving and just a touch with a grinding wheel and diamond hone and it back into use! I do like carbide for cast iron. The main problem is that there are so many grades of carbide that it take a while to get your head around! I'm an electronic & electrical engineer not a mechanical engineer so most of my mech engineering is self taught.

John

I've used an M series for a while and carbide or HSS is fine.

The best thing about carbide is it stays sharp for so long if you are whittling down a big lump and it's great for cast iron

I've recently started using 5% cobalt HSS which is very good for long jobs and has more resistance to heat and friction than standard hss

The more you do the more familiar you will become with tooling types, they all have their place and experimenting is part of the fun and the challenge

I'm moving back to HSS from Carbide, at least for the lathe.

Easy to sharpen, ability to do a really nice finish, and don't chip as easily.

Saying that, I do expect to keep some carbide around; hitting a bit of "chill" in Cast Iron is not a lot of fun with HSS...

Hi All...

Thanks very much for all the informative replies. It's most appreciated. I think I'll stick with HSS as I have lots of tools and blanks. Dad-in-law used to be a fitter and toolmaker and I'm still finding stuff in the drawers in the garage! I've also found a box of milling tools so a milling attachment might be on the cards.

I'll have a go at grinding a couple of tools at the weekend and see how I get on. I'll also have to make a parting tool holder, although I can grind one for small diameter work. I've seen a few simple designs that shouldn't be beyond my present capability!

Cheers

Malc

PS How do I remove the banjo from the Type "M". There's a spacing collar missing from behind the adjusting slot so I've wedged a bit of steel in the gap to avoid breaking the casting when tightening it. I've turned a new collar but I need to remove the banjo to fit it. I don't want to try to remove the stud in case it shears off. I've tried pulling it off but it only comes out so much. I can't find any grub screws or clamps but maybe I'm not looking or pulling hard enough.

Edited By Malcolm Bannister on 16/04/2015 12:52:06

The banjo simply pulls straight off. It may bring the centre pin with it but thats ok

M series lathes make very good small milling units once they are properly set up, they are a very strong stiff hobby lathe

Hi All...

I'll stick with the Norman tool holder for now. It's not much of a hassle to change tools now I've made some shims to drop round the tool holder post for different tool heights. I'll get round to drilling and tapping it for a height adjustment screw as this doesn't have one - unlike the pics that I've seen. Besides, QCTPs and four way tool holders cost a bomb and I'd sooner spend the money on tools and stock.

I've got an idea a tool centre height gauge involving brass rod with a neodymium magnet inset into the base.

I ground a couple of tools today and they work OK. The grinding wheels are in a bit of a state so I need a wheel dresser. Any suggestions for a wheel type versus a diamond type?

Thanks to everybody for their tips and comments. It's making my learning curve a bit less steep!

Malc