|Tom Read||10/11/2018 17:27:12|
|2 forum posts||Hi i have recently brought my first lathe a myford ml7, i have a brought a set of hss 10mm bits but they sit to high, so i guess i need 8mm and shim them up ? |
Also what is better hss or carbide insert bids
|97 forum posts|
As a beginner I feel you would be better with HSS and grind the former yourself there’s a good series in the ME covering this in the last 3-4 issues inserts can be fragile especially to the complete novice and they are comparatively expensive as you will be needing a lot of diverse kit early on to get started. Yes shim them up but it is important to get them exactly on centre height
What type of tool post do you have? One thing is when changing tools, keep each tool with its own set of packings, an elastic band or box with divisions so once set you won’t have to do it again until you have to regrind.
Good luck and keep us posted on your progress
Edit.... ps where are you based?
Edited By Zan on 10/11/2018 19:00:44
|John Baron||10/11/2018 20:08:29|
90 forum posts
If you have the ability, make a "Norman" patent tool post ! I made one for my Myford S7 and can use from 1/4" inch up to 1/2" inch square tool size. Most of the work building one is turning and threading. I posted a picture of mine a short while ago. I also have the drawings based on the original patent by Van Norman.
Its one of those things that I wish I had made years ago. In fact Myford actually produced and sold the ML3 and I believe ML4 lathes with one already fitted.
Forgot to add I use HSS tool bits, the Myford doesn't really have enough speed for making best use of carbide.
Edited By John Baron on 10/11/2018 20:11:43
Edited By John Baron on 10/11/2018 20:12:32
3651 forum posts
You can use 10mm tooling in the ML7 4-way toolpost if you machine about .030" off the base of the toolpost to bring things back down to centre height. This can be done either by holding a milling cutter in the chuck and packing up the toolpost and milling the bottom of the slots the tooling fits into. Or, easier, if you have a second tool post of some sort, hold the toolpost in the four jaw chuck and face .030" off the bottom surface that normally sits on the cross slide.
But if you are using HSS, it's easier to use 8mm(5/16" ) or even 1/4" (6mm) because it takes way less time to grind up a toolbit than a piece of 3/8 or 10mm.
As a beginner you should learn how to grind your own HSS toolbits. It's an essential skill. Sooner or later you will need a special tool that can't be bought. Plus HSS gives a better finish in these small lathes.
Edited By Hopper on 10/11/2018 23:07:45
|Mark Rand||11/11/2018 00:02:47|
|729 forum posts|
I had a four way tool post on the first ML7 I got. On that one and, later dad's long bed ML7B that I inherited, I didn't use it. I found that 12mm tools with dedicated shims directly on the top slide table were as quick and more flexible than the four way tool post.
|1214 forum posts|
The OP doesn't say what tool holding facility he has but I can't help feeling that for most purposes almost anything would be better than the standard sprung clogheel arrangement.
|Jon Lawes||11/11/2018 14:50:54|
313 forum posts
ega, I'm sure there are better arrangements out there but I can't say I've ever felt held back by the standard ML7 toolpost. There are quicker/better systems for sure, but its fairly versatile especially when using various size tools.
|Grizzly bear||11/11/2018 16:06:14|
|200 forum posts|
I may have missed something. With your 10mm bits, grind the end down so they are at centre height.
Then grind the cutting profile, its not critical, if it does not cut well, the grindstone is your friend.
I've used 12.7mm/ 0.5inch, yes, more grinding involved, but if the price is right etc.
Good luck, bear..
|4529 forum posts|
Although HSS is well suited to slowish and less powerful machines it's not necessarily the best choice for a beginner. You need to get hold of a grinder and learn how to use it. And grinding HSS to shape isn't something everyone is automatically good at!
Carbide inserts are a valid alternative for beginners wanting to get started quickly with a new lathe. And for experienced chaps who struggle to sharpen HSS. For a newcomer, the big advantage of carbide inserts is that they don't need to be sharpened. On the downside, carbide works best when worked 4 to 10 times harder than HSS and it can be tricky to get a good finish on a lathe that's short of the necessary power, speed or rigidity. But I find carbide works well enough most of the time for me on modest equipment.
|Tom Read||12/11/2018 18:17:10|
|2 forum posts||Hi, thanks for all the replys its just a manual four way tool post i assume its the one that original comes on them ? Im a mechanic by trade so have grinders and all sorts. I think i will order a 8mm carbide bit on to try for the just for the cost of 20? and will try to sharpen the ones i have and take them down to meet the center height|
|97 forum posts|
Carbide needs a softer wheel than the standard grey/blue wheel. This is commonly known as a green grit wheel in modelling circles. The standard wheel is useless on carbide tooling it is normally finish honed with a diamond lap afterwards. Carbide also need a lot of power to work efficiently. They are particularly useful for matching castings which often have a hard surface skin which will rapidly blunt anHSS tool
Edit. Autotype error
Edited By Zan on 12/11/2018 18:46:13
2426 forum posts
Have you considered getting a tangential tool; initially expensive but you only need one HSS tool bit, & will only need to grind the top face to touch up plus you can set the bit to centre height without having to shim up. There are other members who have made one for their machine & swear by it, & have drawings available if you ask. I have one, bought from Eccentric Engineering, ad on the right, usual disclaimer, & I use it for 90% of my machining. I do have a selection of HSS & indexible tipped cutters but these were bought 'along the way' as we all tend to do.
|988 forum posts|
Decent quality 1/4" Eclipse cobalt was about the only thing i could use on mine if you can still get it.
The only carbide mine would run is the Kennametal Top Notch tools turned down to 14.2mm. Though it did sit in a purpose made 4 way tool post housing boring bores etc ready to go.
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