|Ron Laden||16/07/2019 12:14:26|
1874 forum posts
Last year when I started out and got my mini lathe it came with a set of carbide tipped tools. Not knowing any different at the time I thought great, I could start making swarf...but no.
The tools come shaped (and there are some strange shapes) but none are sharpened or at least mine were not. Some of you guys suggested I shelve them and get myself a decent set of HSS tools and/or blanks and cut my own which I did.
I had forgotten about the tipped set until yesterday when I came across them again. I wondered if some of them were given a good edge how good or bad they would be. I picked out one or two using the ones that were reasonably shaped though I had to change/improve some of the angles.
I put up a piece of free cutting steel as a test piece and gave them a try, I used the smaller of the two knife type on the spigot and the bit heavier version on the shoulder behind. The chamfer tool was a bit of a dogs dinner to start with (still is) but I got a good edge on it and used it between the shoulder and the spigot. The parting tool I used for cutting the groove and the parting off.
Well the tools worked ok, not the very best of finishes but not too bad at all, I was surprised how well the parting tool worked for both grooving and parting off . Although carbide I used them not much above HSS speeds and in fact when I tried running them at higher speeds there was no improvement.
One of the boring tools looks to have a decent shaped bit so that could probably be made good plus there are a couple of others that may turn out ok. I guess there are about six tools from the set of twelve that could be useful.
It was just a bit of a test and obviously I am not recommending the set, far from it but with a bit of work you can get a few usable tools and if they come with the machine why not.
|Neil Wyatt||16/07/2019 13:01:07|
17729 forum posts
Nice one Ron,
These tools will prove their use when you get some really nasty materials or hard-surfaced castings.
|not done it yet||16/07/2019 13:02:03|
|4505 forum posts|
Apart from the shortcomings you have discovered and corrected(?), there is always the possibility that the carbide was of a ‘less than optimum’ grade for most, or many, turning operations.
First thought is that they may well be ground to a point - which is likely the first to chip, without a small radius....
|2494 forum posts|
In spite of grinding to a useable state I’ve still found them rubbish. I know some folks can get on with them though.
2634 forum posts
I only use the brazed carbide L/R hand knife edge on cast iron; cylinders / flywheels & the like, the rest ( most of ) of my cutting is done with a tangential tool with a HSS bit which I bought from 'Eccentric Engineering', see ad on right of page. I do use 'insert' type cutters as well, depending on material & type of finish I can get, but mainly the tangential.
|Ron Laden||16/07/2019 16:50:05|
1874 forum posts
Yes they obviously do have their shortcomings and the carbide probably is of a poor quality but it was interesting to see if they would produce a half decent test piece and they certainly did that but they wouldnt be my cutting tools of choice.
As Neil suggests they may come in one day when there is something nasty to machine. The one tool I will keep handy though is the 3mm parting tool, not for parting but for grooving as that really did work very well.
|Ron Laden||18/07/2019 08:46:25|
1874 forum posts
I knew the grooving tool would come in at some point and its sooner than later, ideal in a tight space. Saved buying more oilites (£20) I modified some I already had.
|5633 forum posts|
I once dismissed fixed tip carbide tools out of hand because they have the skilled-grinding disadvantages of HSS without the quick-change flexibility of carbide inserts. Tipped tools are neither one or the other. Actually they can be jolly useful as a kind of extra-hard HSS, provided they're sharp.
I suspect the main reason they're unpopular is becaue the need to make sure they're sharp on arrival is rarely mentioned. (I only found out via this forum.) Mine arrived with my mini-lathe looking ready to go out of the box and performed badly. No-one told me they needed touching up first, and in my innocence I didn't know what to look for!
I suppose it's also possible that some cheap sets are too cheap.
I wouldn't go out of my way to buy a new carbide tipped set. Most of my turning is done with inserts and the main reason I occasionally get HSS out is because carbide can't get a good finish on my machine. (Fairly certain my finish failures with carbide are because my lathe isn't powerful and rigid enough to reliably get carbide into the zone. It wants another kilowatt, and 200kg of cast-iron rigidity, and an extra 2000rpm on the spindle.)
HSS and inserts meet all of my needs, which might be because I rarely turn difficult materials into intricate shapes. Learning to select the best tool for the job is all part of the fun!
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