Needed: Suggestions for 'starter' milling cutters for lathe milling attachment

[PeterT]

from what i understand roughing endmills actually take more hp and rigidity, but maybe that's to take full advantage of the roughing action, im not sure

My experience has been the opposite. For the same material removal, roughers put less stress on lighter duty machines & make better use of limited HP so actually more beneficial. I highly recommend them. They make a very efficient chip. Some notes

- they typically make roughers in fine & coarse depending on size. You might want to try one of each to see which you prefer & what your machine likes. In terms of end cutting, they make a pretty decent finish. Sometimes on non-critical parts I don't even bother swapping in a regular EM. Side milling of course leaves little serrations on the part.

- they will be metric on Ali, so hopefully you have an ER or some collet system to accommodate

- what I find advantageous is but a rougher same diameter as regular/finishing EM. That way you can hog out your work, leave some allowance, then plop the regular EM in & your dimensions & settings stay mostly the same. I say mostly because all EM's have tolerance. The roughers are a bit more +/-

Do some poking around AliExpress, there's lots of sales & coupons going on now it seems.

 

[VicHobbyGuy]

Thanks, @PeterT . I bought a pair of those roughing cutters just now. I do have ER32 collets in both metric and inch sizes, so plenty of choices. Because metric drills, taps, reamers, etc are all so much cheaper from China than the inch equivalents from N.A., I've been working more and more in metric lately. And buying metric fasteners from China, too.

 

[Dabbler]

I’m with Degen. My choice would be 1/4”, 3/8”, 1/2” in HSS.

I'm kinda late to the discussion... To get started, and to keep the HP requirements I'd start with a pair of 1/2" HSS 2 flute double ended cutting tools. Because your setup won't be very rigid, you are quite limited in how small you can go. I wouldn't choose a rougher end mill as they really shine in side milling, but your least pressure cut is by plunge milling. Roughing end mills have no significant advantage in plunging operations.

Why 1/2" to start? because it is nearly twice as hard to break a 1/2" end mill than a 3/8 end mill. After you get really confident and experienced in milling operations you can go to 3/8 HSS, and finally to carbide. I started milling with a lathe milling attachment (now owned by @DavidR8) over 40 years ago. I broke too many cutters at first.

I would stay away from carbide to start with until you get more experience. Because you aren't too rigid, and unless you get specific 2 flute carbide honed and polished carbide end mills (ground for aluminum), your carbide end mill will always require more cutting forces than an HS tool. You may well soon graduate to carbide, but the HSS will tell you what your lathe can do, and what you can do with your lathe (very different things).

You can resharpen these end mills using a diamond hone until you get more machines and a better setup. Bonus.

oops I missed the race, @VicHobbyGuy

 

[phaxtris]

My experience has been the opposite. For the same material removal, roughers put less stress on lighter duty machines & make better use of limited HP so actually more beneficial. I highly recommend them. They make a very efficient chip. Some notes

Oh yes I see I had that backwards, I have only ever had one rougher and burned it up in about 5 minutes (steel, hss endmill), haven't bothered with them since, maybe I'll order a few carbide ones and see how I like them

 

[Dabbler]

@phaxtris burning up a HSS rougher is easy to do... You have to lower your feed rate considerably to do thos deep cuts on side milling. I don;t use roughers because they are nearly impossible to sharpen, and they do dull quicker than spiral flute cutters.

 

[VicHobbyGuy]

oops I missed the race, @VicHobbyGuy

No worries : On AliExpress 'spares' like those roughers are pretty cheap.

Thanks for all that info - I hadn't considered the breakage issue and I'd assumed that a 1/4" cutter would require less power than a 1/2".

I've been told (on another forum/group) to avoid climb cutting when milling on the lathe. Do you agree?

I took your advice and trotted off to AliExpress and bought a few 1/2" 2 flute HSS cutters. They don't have double-ended ones as far as I could see, which is fine with me as I would worry about chewing up my collets through negligence. Since it's AliExpress, I'll get back to you folks in a month or two with some feedback on how those particular cutters worked out for me!

 

[Dabbler]

-- you shouldn't climb mill on a lathe. There is far too much flexibility and backlash in the system. Even conventional milling as 'side milling' needs very shallow cuts. I found much more success plunge milling, and then side milling the last thou or 2 for finish (but never climb)

 

[VicHobbyGuy]

-- you shouldn't climb mill on a lathe. There is far too much flexibility and backlash in the system. Even conventional milling as 'side milling' needs very shallow cuts. I found much more success plunge milling, and then side milling the last thou or 2 for finish (but never climb)

Thanks, I'll keep that in mind. I've done a lot of router work on wood, so I'm pretty aware of cutting direction, though with wood, climb cutting can be very useful.

 

[Susquatch]

Thanks, I'll keep that in mind. I've done a lot of router work on wood, so I'm pretty aware of cutting direction, though with wood, climb cutting can be very useful.

As a relative newcomer to milling metal myself, I'd like to add a few comments that might not be obvious. I've been using a lathe for decades, but only used a converted drill press and then a mill/drill for light milling till I got a full size Bridgeport Clone last year.

First off, conventional milling leaves more burrs than climb milling. But conventional Milling leaves a much better finish. I'll take a good finish over a few burrs any day of the week.

Secondly, as a newbie myself, my "apparent" skills skyrocketed the day I bought some good HSS bits. I started with Carbide and even broke one climb milling - prolly had the feed rate a little too fast on a mill with way too much backlash. But HSS cut beautiful right from the git go. Not sayin it's better here, just saying it made a newbie like me "look" better than he really is. I like that......

LOCK THOSE GIBS. This made a huge difference for me. Nobody says that to you when you are starting out. Well, nobody but @Dabbler that is. He is the one who realized that I didn't know that. But he isn't always around to help out. I think he spends all his time helping others.....

Always lock the Gibbs on the the two axis you are not using. Even on a mill with low backlash, this can suddenly bite you. And the less rigidity you have, the more likely that flexing will add to the drama.

 

[PeterT]

But conventional Milling leaves a much better finish. I'll take a good finish over a few burrs any day of the week.

Assume you are talking about the surface being milled by side of EM. I think this goes against longstanding milling practice based on the chip thickness profile as a function of direction. Now if you mean what is better on a loose machine, that's maybe a different discussion,

Climb Milling is generally the best way to machine parts today since it reduces the load from the cutting edge, leaves a better surface finish, and improves tool life. During Conventional Milling, the cutter tends to dig into the workpiece and may cause the part to be cut out of tolerance.

Climb Milling vs. Conventional Milling - In The Loupe

Follow along for the differences in Climb Vs. Conventional milling, and why to choose one strategy over another in your shop.

www.harveyperformance.com

 

[Susquatch]

Assume you are talking about the surface being milled by side of EM. I think this goes against longstanding milling practice based on the chip thickness profile as a function of direction. Now if you mean what is better on a loose machine, that's maybe a different discussion,

Climb Milling is generally the best way to machine parts today since it reduces the load from the cutting edge, leaves a better surface finish, and improves tool life. During Conventional Milling, the cutter tends to dig into the workpiece and may cause the part to be cut out of tolerance.

Climb Milling vs. Conventional Milling - In The Loupe

Follow along for the differences in Climb Vs. Conventional milling, and why to choose one strategy over another in your shop.

www.harveyperformance.com

OK, I'll bite.

No, I was talking end milling not side milling. Yes, I agree that for side milling, climb milling produces a better finish. That's been my experience too. But I don't think most new machinists start off side milling. I didn't. In the case of side milling, I cut conventionally till the final pass and then just take a skim cut with climb milling - with a tight Gibb lock.

Very interesting article. It is cool to see how things change with knowledge and newer better machines.

I do get the distinct impression that it was written in the context of a professional environment - big tight CNC machines with insert tooling. That may be you, but it sure as heck isn't me. I don't think it's good advice for the average hobbiest with a small mill either. But that is just my opinion.

So I took the time to see what else is out there for a newbie. Seems it's pretty much what I suggested to @VicHobbyGuy.

As a newcomer to all this milling voodoo, no climb milling for me except where specifically called for or when it doesn't matter. I tried it and I didn't like it! Too easy for a new machinist to get in way over his head. Maybe I shouldn't be giving advice to other newbies like myself. But if they only get the pro advice, they might be very disappointed and might even break something serious. I wish somebody had told me this when I first started. As it is, I only snapped a carbide end mill. It could have been much worse. Gotta learn to walk before you run.....

Much as I hate YouTube, I attach the following video that I think does a very good job of balancing the info for newbies and pros alike. As a relative newbie to milling myself, I found it both informative and not too focussed on entertainment. Which I like. I'm sure there is nothing new in the video for you @PeterT , but I learned a few more things I didn't know and I really liked how he demonstrated the danger of climb milling as well as ways to avoid such problems. You might not agree but I think it strikes the right balance between advice for new comers like me with smaller or looser machines and old pros like you.

 

[PeterT]

The thing is, unless a new machinist is confined to milling top surfaces of a smallish blocks, he should be cognizant of EM cutting direction very early on in the game IMO. Because even the simplest of any inside feature will (should) present that consideration. On hobby class machine or looser machine, you can remove more material, safer in conventional mode & achieve better finishing in climb mode. This become even more important if not critical as projects progress, dovetails, slitting saws.... For that matter consider a very simple rectangular stick say 0.5x1x4". You are not going to stand that up in the vise to mill the ends square & to length, so right there, project number 0.5 ... to climb or not to climb, that is the question. LOL

 

[PeterT]

Re the video, I know we have discussed collets and (biggish) cutters before. Sorry but not having the right holder is kind of weak IMO. I assume that's an R8 (bottom slit style) style collet. With a big EM he's asking for trouble including breaking it and/or ruining the work if conditions go slightly sideways like catching a tooth, runout, loose table.... Which, would probably make a good down payment on a holder.
R8 style collets can only collapse on the bottom & that is where the grip band is focused. An ER style collet is better choice in that it collapses diametrically because the spring slits alternate from either end of collet. An EM holder is a accurate bore with a big fat set screw 'key' which absorbs all the torque load in. Yes EM's are generally sized pretty close to their nominal dimension so should be a pretty tight fit in an R8. I'm not saying to wont work, because it will... until it doesn't. But there is a better way.

 

[Susquatch]

The thing is, unless a new machinist is confined to milling top surfaces of a smallish blocks, he should be cognizant of EM cutting direction very early on in the game IMO.

Now THAT I'll agree with! The problem is that nobody tells us that! At least not at the right time...... So most of us are left to snap an endmill or worse! I feel it's best to tell newbies that and then tell them to conventional mill until they understand. But that's only my view.

On hobby class machine or looser machine, you can remove more material, safer in conventional mode & achieve better finishing in climb mode. This become even more important if not critical as projects progress, dovetails, slitting saws....

Yup yup and yup!

For that matter consider a very simple rectangular stick say 0.5x1x4". You are not going to stand that up in the vise to mill the ends square & to length, so right there, project number 0.5 ... to climb or not to climb, that is the question. LOL

Ya, Tom did that in video, but he did it deliberately to show what happens and he explained that too.

Re the video, I know we have discussed collets and (biggish) cutters before. Sorry but not having the right holder is kind of weak IMO. I assume that's an R8 (bottom slit style) style collet. With a big EM he's asking for trouble including breaking it and/or ruining the work if conditions go slightly sideways like catching a tooth, runout, loose table.... Which, would probably make a good down payment on a holder.

I thought he explained that too. Maybe I just assumed he did.

R8 style collets can only collapse on the bottom & that is where the grip band is focused. An ER style collet is better choice in that it collapses diametrically because the spring slits alternate from either end of collet. An EM holder is a accurate bore with a big fat set screw 'key' which absorbs all the torque load in. Yes EM's are generally sized pretty close to their nominal dimension so should be a pretty tight fit in an R8. I'm not saying to wont work, because it will... until it doesn't. But there is a better way.

This is an interesting point. Good luck explaining that to a fellow who just bought their first mill that came with R8 collets.

I'm not sure this point really matters much with a small mill though.

Ive been looking for an inexpensive but decent quality R8 Endmill Holders without much success. I may have to pay through the nose for a few good ones in 6mm 12mm 1/4 3/8 & 1/2. I don't think it make sense to put together a full set one at a time. But even these 5 will set me back $300 plus for good ones.

 

[Dabbler]

@PeterT I agree that R8 only clamps on the bottom, but the difference is a little more theoretical than I think you are implying. I've used R8 collets for 40 years with great results. I've used ER collets for 20 years with great results. I think they both work well enough in practical situations.

 

[PeterT]

Ive been looking for an inexpensive but decent quality R8 Endmill Holders without much success. I may have to pay through the nose for a few good ones in 6mm 12mm 1/4 3/8 & 1/2. I don't think it make sense to put together a full set one at a time. But even these 5 will set me back $300 plus for good ones.

I went down that path too & why I only have a few nominal-inch holders & hit pause. I discovered there is a whole big world of high quality metric EM's out there at significantly lower cost than I can typically get domestically. I actually started needing metric EM's here & there & for the most part it doesn't really matter what the nominal OD is as long as it suites the cutting job. So shifted my thinking. Unlike the N-Am standard that (kind of) unifies on certain shank standards like 1/4, 3/8, 1/2", metric EMs are more typically EM diameter = shank dia. There are exceptions but this is the norm. So now the options are metric R8 set or ER holder+collet set, choose your poison. With ER you can hold imperial or metric EM's, they have a wider holding capacity per collet. So different ways to skin the cat & vacate the piggy bank.

I somehow got buy with very few R8 collets for the mill given I use other holders. But I may have to spring for some at some point to make proper use of the cutter grinder. Been eyeing these.

Colton Industrial Tools 20110 | 25 Piece Ultra Precision R8 Round Collet Set, 1/8" - 7/8" x 1/32" Increments, 0.0005" Accuracy

We distribute top-quality industrial tools and machine shop supplies at the best prices. View our collection of CNC machinist supplies and tooling packages.

allindustrial.com

 

[Susquatch]

I went down that path too & why I only have a few nominal-inch holders & hit pause. I discovered there is a whole big world of high quality metric EM's out there at significantly lower cost than I can typically get domestically. I actually started needing metric EM's here & there & for the most part it doesn't really matter what the nominal OD is as long as it suites the cutting job. So shifted my thinking. Unlike the N-Am standard that (kind of) unifies on certain shank standards like 1/4, 3/8, 1/2", metric EMs are more typically EM diameter = shank dia. There are exceptions but this is the norm. So now the options are metric R8 set or ER holder+collet set, choose your poison. With ER you can hold imperial or metric EM's, they have a wider holding capacity per collet. So different ways to skin the cat & vacate the piggy bank.

I somehow got buy with very few R8 collets for the mill given I use other holders. But I may have to spring for some at some point to make proper use of the cutter grinder. Been eyeing these.

Colton Industrial Tools 20110 | 25 Piece Ultra Precision R8 Round Collet Set, 1/8" - 7/8" x 1/32" Increments, 0.0005" Accuracy

We distribute top-quality industrial tools and machine shop supplies at the best prices. View our collection of CNC machinist supplies and tooling packages.

allindustrial.com

I think @Dabbler is prolly right. It's unlikely that there is a huge real world difference.

But I'd like to get a "few" end mill holders. Perhaps just 4 of them (6 & 12 & 1/4 & 1/2). Not for rigidity but rather for rough indexing. My new DRO will save up to 200 relative dimensions that can be used for tooling. I'm not sure how useful it really is just yet, but who knows. Nothing ventured, nothing gained.

On the other hand I do have a half set of ER32 collets (16ths) as well as an R8 - ER32 holder so I should give that a whirl too.