Milling on a lathe

[Chris FarbraceParticipant @chrisfarbrace]

Hello,first of all thanks to everyone who steered me towards purchasing a diamond tool holder after poor results using carbide tools on my Sieg C4,a great improvement and I can recommend using the UK link on their website to purchase these I got mine in just a couple of days(using Paypal).Next,I dont have the funds available yet to purchase a stand alone mill but am considering  buying a heavy duty vertical slide from Chronos which I am sure I could fit(maybe making up an adaptor plate)to the slotted crosslide on my lathe.Has anyone bought one of these?are they any good?I think I understand that a slot drill is for plunging into the work and milling a slot but would one be used to create a flat bottomed hole to take socket head(allen) screw heads flush with the surface of the work(just like you would countersink or counterbore in woodwork)and does anyone have any general advice about buying milling cutters or their use in such a setup,Ido have an ER32 collet/chuck set which would hold the cutters but any advice from the experts about my ideas  would as ususal be gratefully received many thanks,kind regards Chris Farbrace

[Chris FarbraceParticipant @chrisfarbrace]

[mgjParticipant @mgj]

Allen bolts, slot drills and flat bottomed holes. Yes, works well.

 

Others will have to answer for the slide and the collets. I use ER32 collets but have no experience of htem as a cutter holding device, but I understand they can be used for that.

[chris stephensParticipant @chrisstephens63393]

Meyrick oh Meyrick,

ER collets are only “recommended” for holding tooling, not for holding work.

I know we all do it, but , as someone will probably say “it doesn’t make it right or safe”.

I think it is not that it unsafe to hold work in an ER, it is just that tool holding needs less accuracy than work holding. A few micron run out on an end mill will bother no one, but might make a wheel on an axle might bind . What say you, proper engineers? Discuss! 

chris stephens

[BobParticipant @bob17059]

Hi All

 

I agree that a slot drill can be used to flat bottom or counterbore a hole, but take great care, especially when counterboring this way. If the lip of the slot drill takes hold of one side of the hole it can exert a lot of force on the work/machine and if there is not sufficient rigidity something will give. Either the work will move or the slot drill will break. Best to use a twist drill to at least start the counterbore before finally squaring off the bottom. A better solution is to use a proper counterbore with a fixed pilot.

 

With regard to holding slot drills, remember if they are not central to their axis if rotation they will cut oversize so collet chucks or accurately bored holders (like FC3 holders) are the way to go.

 

No experience of using ER collets, but as long as the stock you fit into the collet is well finished, parallel and to size or a tiny (say 0.002″ under no more) then you should have no problems.

 

Bob

[mgjParticipant @mgj]

ER collets- I stand corrected – ain’t going to change what I do though.

 

I don’t believe my 100mm  ER 32  collet chuck fitted with its D1-4 camlock back was for tooling. Most lathes like that don’t have slots for a milling table!

 

—-

 

I’m not quite sure how the edge of a slot drill is to catch on anything.

 

I drill a hole for the screw or bolt. I move nothing other than to put a (larger) slot drill in place to accomodate the socket cap head, and I downfeed to depth.  

Edited By meyrick griffith-jones on 12/11/2009 18:26:15

[chris stephensParticipant @chrisstephens63393]

Meyrick, We mustn’t go on meeting like this people will begin to suspect!

If you look at the genuine type of ER collet holders they are all taper fitting, morse, R8 or INT, the back plated ones are after market ,far eastern, lets-fill-a-gap-in-the-market and supply what people want ones. 

Having said that, I want to get an ER32 one for my Myford, I am one of those whose gap in the market they can fill. Hell, if it works, it works!

chris stephens

[mgjParticipant @mgj]

Well I can see they would be good for toolholding, and probably more flexible than a Posi/Autolock. I should probably have bought a decent R8 ER32 holder against a Pozilock – thinking about it. Just on the basis of amount of capabiltiy for the money,

 

Fitting to a Myford. I did a backplate fitting one for the Chinaman  (ER32), and bought a good screw on one for the Myford (ER25).  The backplate fitted one is a lot more accurate.  – because I made sure it was.  Might steer ones thinking.

[John HaineParticipant @johnhaine32865]

Chris,

 

When I got my VMB I did as Myford recommended and got the R8 taper.  On my old mill I had a Pozilock (MT2), but I bought R8 collets for the VMB and have never missed the old Pozilock.  They are excellent, minimum overhang, tight cutter holding, accurate, and the collets are economical to buy as they are used widely in the Bridgeport (I think).  Never again will I use a separate collet chuck if I can avoid it.  On that experience I would recommend using collets direct in the lathe spindle taper for milling in the lathe if you can get them.

 

I have used both slot and and mills for counterboring – as long as the smaller hole is drilled first an end mill should work.  As someone above suggested, best to first drill the counterbore with a normal  drill and just use the cutter to “flat bottom” the hole.  This however is in the mill, probably a bit more rigid than the lathe vertical slide so go carefully.

 

John.

[chris stephensParticipant @chrisstephens63393]

Hi John,

I have the R8 oriental made posilock that came with the mill, but haven’t used them for years. I also have an R8 ER32 collet set and R8 collets in the most used sizes, IMP and metric. It is these that I use the most and find them V. convenient, except for 6mm throw away cutters for these I made an extension piece to fit a 10 mm collet, this gives a little more working height. For drills up to 10 mm I made a short straight arbour for a keyless chuck, which fits in a 1/2″ collet. For bigger drills I use my ER collets, which is now about the only time I  use them.

You have given me an idea, I shall investigate to see if 5C collets can be fitted into the headstock of the Bantam, with only a minimal “fixture”. I have avoided this before because the lathe is too close to a wall, and drifting out anything in the headstock has been problematical. Certainly there is no room for a closing tube. This winter I aim to swap the shop around and not make the same mistake again. It wont help with the super precision  collets I have, though.

chris stephens

[VersabossParticipant @versaboss]

Chris oh Chris, (to repeat your opener),

yes I am not a proper engineer. But I know one thing: ER collets have been invented (in Switzerland as far as I know) for toolholding. What do you think that all those ten-thousands of CNC mills use? And the idea that toolholding requires less precision than workholding – naa, I don’t think so. When a end mill has runout, then how on earth do you know the correct tool diameter compensation?

Greetings, Versaboss

[chris stephensParticipant @chrisstephens63393]

Hi Versaboss

Re tool holding I thought that was what I wrote. 

I also mentioned microns as run out, this is less than most tolerances quoted in drawings, and i would be surprised if many CNC machines work to this degree of accuracy on a regular basis. The point about work being out was merely used as an example, not for any particular case.

Yes, I believe you are right about the Swiss inventing the ER collet system.

Hope this clarifies the matter, we really are not disagreeing on substantive issues.

chris stephens

[VersabossParticipant @versaboss]

Sorry Chris, if I misinterpreted the “recommended”. My excuse: it was a bit late in the night. Yes, we don’t disagree.

Greetings, Versaboss (Hansrudolf)

[Chris FarbraceParticipant @chrisfarbrace]

Sorry forgot my manners and didnt post a reply on this one but thanks to all for the replies I now have a better idea of what to try.regards,Chris Farbrace

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