HSS vs carbide inserts

Sean

The ML1 is a pretty old lady now and it might be kinder ( and more successful) for you to use HSS - At least until you both know each other better!

Norman

First it depends upon the insert. There are many obsolete inserts around for which holders are no longer available. Even if the insert isn't obsolete you then need to consider tool holder size. Most modern insert holders start at 16mm and go upwards. Smaller 8mm and 12mm holders are available, but are less common. To make any sort of sensible comment we really need to see a picture of the inserts.

The other issue with inserts is that, with common low carbon steels, they really need to be run fairly fast and hard in terms of feedrates to get a good finish.

In short I agree with Norman, I don't think the ML1 is likely to have the rigidity, spindle speed or horsepower to make use of carbide inserts.

Grind your own HSS tools; despite the myths it is pretty straightforward. All you really need is a bench grinder.

Andrew

Hi ya. Carbide inserts are ready to use straight from the box and usually they are clamped or held in position with a screw . The original idea was to save on discrepancy in grinding and generally obtain a better finish ,but there were some compromises with the spindle speed if you had mixed tool set up IE HSS drills taps etc and overlapping operations. HSStooling generally works out cheaper because it can be ground by hand and reground many times and in many forms parting off turning and chamfering to name a few Today in most machine shops there will be some CNCs and the carbide inset as come into its own mainly because of repeatability, all you have to do is turn the tip round over etc and the machined sizes e should be as was before the tip started wearing .Hope this helps and have fond with your lathe Stewart

Grind whatever shape you like in solid metal, the humble hss square is the first line of defence, no matter what fancies a tip may have, it will always be there for you.

Michael W

I wonder - why has no-one offered HSS inserts for us amateurs to use on the carbide holders we bought and then put to one side?

Or if they do, name & address, please.

Cheers, Tim

The business opportunity is all yours to exploit.

Although I'm afraid I won't be buying as I haven't put any of my insert holders aside yet.

Andrew

I think you failed to notice the word 'amateurs', Andrew

Tim

Hi Tim,

Is this what you were looking for?

Thor

Hello Thor

Yes, some of the list you linked may well be just what I need, so is there a UK source? US stuff always comes with a massive postal bill ...

Cheers, Tim

Hi Tim,

Sorry, I haven't seen any distributors this side of the Atlantic. Yes, delivery costs across the Atlantic are high, not cheap across the North Sea either.

Thor

Tim, Re HSS inserts Arno werkzeuge do hss in most of the carbide geometries Here is a box I got at a good discount but are still very spendy

Which hss tool should I go for and will a regular bench grinder suffice ?

Delivery costs from US to Canada are no better, even if we are just on top of them. I just ordered a casting kit from PM Research in NY State. Their address is about 100 km from a border crossing - which also happens to be the closest border crossing to my home (about the same distance). The kit was $129.00 ; the shipping was $43.65.

(It was taken to NYC first and flown it in from there).

Most of the stuff I machine can be done quite easily using HSS. The only exception is cast iron castings and my collection of ancient CI sash weights. Here I use/experiment with a variety of carbide inserts purchased cheaply from ebay or boot sales with varying results. Needless to say, one or more types of insert usually get the dirty work done!

Rik

FWIW, I usually get better results in those cases using the brazed carbide toolbits rather than inserts.

I agree, brazed carbide takes a lot more abuse than inserts. I managed to machine some Sweet Pea wheels which were full of hard spots, they had defeated all HSS and inserts. However, for an ML1 I'd stick with HSS, if you really can't get to grips with tool grinding make (or buy) a tangential toolholder, then sharpening is simplicity itself. However, tool grinding is not that difficut, none of the angles are that important despite what the books say, and you can use diamond files to put tip radii on if you're not confident to do it on a bench grinder.

I think an ML1 might be a bit like my 1937 M-type when it comes to carbide inserts. The flat belts will slip under the load of carbide tooling, allowing the spindle to almost stall, tearing the point off the tool. Very frustrating.

Learn to sharpen HSS. You will never be sorry. LH Sparey's book "The Amateur's Lathe" has a very good but simple rundown on how-to. To get started all you need is a basic knife tool. You just put a 15-degree angle on three faces of a tool bit blank and away you go. The angle can be within 5 or even 10 degrees each way of the desired 15 and the tool will still work.. No need for fancy rests and attachments. A standard six-inch bench grinder with standard coarse and fine wheels will do the job perfectly. You might practice first on some bits of scrap square mild steel bar to the get the feel of it.

Take time to sit down and study the subject, and then to practice it in the workshop until you get the hang of it. You will be rewarded many times over for the little bit of time invested.

+1

I made my own and keep two double ended pieces of toolbit sharpened on the go. So that as soon as the edge gets too dull I can put in another and carry on. It's as close to indexable HSS tips as I'll be going.

Once you're comfortable with grinding what you have I'd recommend cobalt if you're buying new HSS - M35 (5%) or M42 (8%) for preference. Fewer trips to the grinder and it'll cope with tougher material.

HTH

Jon

Just buy some 1/4 in square HSS blanks and a cheap and cheerful bench grinder. First tool to grind is a right hand knife tool. That will get you started at minimum cost.

Russell