|Tim Richards||29/06/2014 12:33:31|
|7 forum posts|
I am turning EN8 steel for a cylinder but the finish I'm getting seems a bit rough I have tried a new tip in the tool and played around with the speed, any one any ideas
1124 forum posts
Hi Tim, I use EN8 frequently and find HSS works far better than disposable tip tools, indeed I find this to be the case in most instances. Tipped tools are best useD at higher speeds and flooded with coolant but for most home users this is not always possible.
I would grind a HSS tool with a small corner radius say .030" or grind with a chip breaker on the top. Would be useful to know what diameter you are working on.
|Andrew Johnston||29/06/2014 17:17:16|
6405 forum posts
Tim: In order to get a decent finish on EN8 with carbide inserts I find that you need to run at high sfm. See my post towards the end of page 1 on this thread:
In general I find that coolant doesn't make a huge difference to the finish. If you're going to use coolant, then make sure it is a flood (anything else is a waste of time), but it is not essential. I don't use coolant when turning with inserts simply because at the spindle speeds involved it ends up all over the floor and up the wall behind the lathe.
|Ian S C||30/06/2014 12:34:04|
7468 forum posts
One of the local engineering shops here gave up on carbide tips a few years back, and went back to HSS, They rebore hydraulic cylinders on a large, old DSG lathe, but they could not get enough revs to ensure a good finish. They also make new cylinders, and rams. Ian S C
|Trevor Wright||30/06/2014 12:53:50|
139 forum posts
I go along with John but would grind a rake of around 15-20°, slow the speed and flood coolant or WD40. Rough to size with tips but use this tool to generate a nice finish.
Have cut the stuff with carbide tips but you need an industrial size machine to cope with the loads and speeds, and collars buttoned and sleeves down if you don't want some serious burns - the one down an open shirt is not pleasant as it burns all the way down as you waft the shirt. Or it burns into the skin and does the fingers as you frantically try to extricate it. You very quickly work out where not to stand.........
Edited By Trevor Wright on 30/06/2014 12:54:13
|Steve Withnell||30/06/2014 13:20:44|
843 forum posts
This feels like I'm swanking a bit - however here is a crankshaft I made made from EN8. All done with HSS on a Sieg C6B lathe. Sharp HSS is the way to go to get a good finish, with the tool height set right and the tool the right shape. I have no facility to deliver flood coolant, so can't comment on that.
Although my lathe will run at 2500 rpm and I can take decent cuts with tip tools, and it will deliver a good finish, it's all bit too frantic when I'm trying to get those tiny journals dead to size. (Within the ability to measure of course...)
|Nigel McBurney 1||30/06/2014 14:27:08|
965 forum posts
There was some years ago in letters to the editor of model engineer ,there must have been a query on surface finish the writer in reply stated that he had worked in a Manchester factory (Location Trafford Park I think) and the turners there would when machining the medium and tough steels , used very low speeds and the tool slightly above centre to get very good surface finish. I tried this out and it works,the use of slow speed has more effect than the tool being above centre height, of course these turners may have been working on large diameters where a small amount above centre probably cause a slight rubbing action which would tend to polish the surface, On EN8 I now machine at about 30 ft a minute plus HSS tools for finish cuts and get very goods results ( Myford and Colchesters) it takes a time but the result is worth it, If there is a lot of metal to be removed prior to finishing I tend to use indexable tips with plenty of lubricant ,to save time and avoid miles of long bits of curly swarf .
|Boiler Bri||30/08/2014 19:48:59|
840 forum posts
704 forum posts
Want a beautiful finish on any steel? Try the vertical shear tool in HSS as described exactly on the Gadget Builder website. Nothing better, easy for taking a half thou cut. I have one for the shaper and the lathe. Who needs surface or cylindrical grinders? They are that good. And check the swarf out!
|Michael Horner||31/08/2014 07:28:20|
|221 forum posts|
Your swanking !
I am on my 5th attempt at this crankshaft
|Oompa Lumpa||31/08/2014 08:43:42|
|888 forum posts|
I have a 4" x 3' bar of EN8 that I cut slices from once in a while. In fact I did this just the other day to make a collar for my Drill Press shown in my Elliott Drill Press thread.
I achieved a beautiful finish using tipped tools. Almost mirror polish. However, and there is a big however, it was done almost by accident. I bought some tooling and along with the tooling were some boxes of tips. All the same CCMT format but different manufacturers, working my through them, as you do, I reached the box marked Widia Valenite and these tips are just dynamite on EN8. I have scoured the Internet without success looking for the exact same tips with the same reference code (not the tip code, that is pretty generic) but so far no success.
The problem we little guys have, is that we can't get manufacturers support to come down and throw a load of research and development knowledge at us. That would make it too easy. I agree, HSS is the way forward here but it would be nice to find another box of those tips.
Oh, and the advice about long sleeves here, I burned my arm pretty badly. I am a pretty stubborn dumbass some days and as I was on a bit of a roll I just refused to stop. The swarf burned actually through the carpet as it was landing on the floor so it burned my arm pretty badly. It'll heal.
|Les Jones 1||31/08/2014 09:01:09|
|2243 forum posts|
To save others having to search for information on the "vertical shear tool" that "thaiguzzi" mentioned here is the link.
|Steve Withnell||31/08/2014 09:11:34|
843 forum posts
Here is one I prepared earlier:
Again EN8, roughed out with tip tools as far as possible then many hours with tiny HSS bit's (eg using what would conventionally be parting off tools with a bespoke "grind".
I did try to straighten it in the lathe, but it broke...
22011 forum posts
I've been switching from CCMT to CCGT for the last few passes on EN8 and have got a very good finish with these tips that are meant for Ali and non-ferrous. All but the two pins and the 5mm dia bit at the end are straight off a CCGT tip.
|Bob Rodgerson||31/08/2014 12:48:50|
|609 forum posts|
I think I posted before about turning crankshafts, in order to stiffen up a flat six crankshaft I machined I filled the gaps between completed webs with resin (not epoxy but Polyester resin) after each one was macined. I then melted the resin by dunking the whole thing in a bucket full of Acetone. It seemed to work well for me.
|Boiler Bri||31/08/2014 17:45:05|
840 forum posts
Jason your work is to be admired and most of us wish we could produce the amount of work that you turn out, however the day job and domestic scene get in my way + travelling to Wales most weekends.
I have now moved the con rod to the miller to put the flats on it.
Rather than multi- cut with an end mill I decided to fly cut it. I will probably have to emery the finish a little but it seems to cut ok.
When I finish it with the fly cutter I will try a faster rotation and take about .1 mm cut
|Andrew Moyes 1||01/09/2014 13:23:09|
|142 forum posts|
Thanks to ‘thaiguzzi’ and Les for the link to the vertical shear tool. Fascinating, and quite unlike any other lathe tool I have seen described elsewhere. I tried it and can confirm all that is said on the link – good finish, ability to take a very fine cuts but tool wears quickly etc.
The main drawback seems to be that it can’t be used to finish right up to a shoulder or turn a crank between webs. But it certainly has its uses.
|2 forum posts||
Unfortunately, as is so often the case in the world of manufacturing today, I have it upon rumor that Valenite has been purchased by another manufacturer. (A web search might shed more light on this, but wading through the incidentals is hardly worth it.) Of course, when these "mergers and acquisitions" occur the slower moving products or products that overlap (at least in the eyes of the marketers) are discontinued. I wonder if I am alone but I have noticed a wide variation in the quality of carbide inserts. Another product, now difficult to purchase, was VR Wesson, Tantung G, which has all the good properties of HSS and is very tough. At one time it was marketed as useful for lathes "incapable of high speed and underpowered". I use it to thread stainless steels. Type 303, free machining is very good, but 304, etc. are gummy and even finishing with a die can pull threads. Bah!
704 forum posts
Yeah, sorry, bit thick with a computer. Back to the tool - it is also a ridiculous easy grind to shape. Mine has the radius so i can face with it too. The shaper tool is in the Moltrecht books.
|326 forum posts|
Does EN8 silver solder ok with the usual easyflo flux?
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