VEVOR 7X14 Lathe converted to a dedicated horizontal mill.

[ttabbal]

I understand that a three jawed lathe chuck is not ideal to use as a mill holder.
At this point I don't really know enough about milling
To make a educated decision on what I need.
I will be researching this upgrade because I know I have options.
Oh by the way what is a draw bar?
Thanks

The draw bar holds the MT3 taper in place so it can't pull out of place. You don't have to buy it, you have a lathe. Turn a chunk of aluminum to fit in the other end of the spindle and with a step to seat against the spindle end. Run a threaded rod through and into the collet/holder. Use a nut to snug it up. To remove, loosen the nut and tap the end with a hammer, preferably non-marring. It doesn't take a lot of torque, I believe about 40 ft-lb for MT. ER types need almost 100 ft-lb.

If you were interested in ER collets anyway, they are a good choice. You can get ER holders that adapt to MT3, or that mount in place of your 3-jaw. There are pros and cons to both types.

If you want collets without the adapters, there are MT3 collets around. They might be a good choice for your application, but it would require you to get right up on the spindle as there is not much stick-out with them. It is likely the most rigid setup for this, and would likely have the lowest runout as there are fewer interfaces.

The big pro right now for an MT3 end mill holder is that they are cheap. So you can take your time on the more expensive products like collets and holders.

 

[steelcat]

A drawbar passes thru the spindle and fastens collets. It's usually threaded on both ends. Some collet systems don't use a drawbar,
such as spindle nose-mounted collet chucks. ER collets are that way

Gotcha! thanks!

The draw bar holds the MT3 taper in place so it can't pull out of place. You don't have to buy it, you have a lathe. Turn a chunk of aluminum to fit in the other end of the spindle and with a step to seat against the spindle end. Run a threaded rod through and into the collet/holder. Use a nut to snug it up. To remove, loosen the nut and tap the end with a hammer, preferably non-marring. It doesn't take a lot of torque, I believe about 40 ft-lb for MT. ER types need almost 100 ft-lb.

If you were interested in ER collets anyway, they are a good choice. You can get ER holders that adapt to MT3, or that mount in place of your 3-jaw. There are pros and cons to both types.

If you want collets without the adapters, there are MT3 collets around. They might be a good choice for your application, but it would require you to get right up on the spindle as there is not much stick-out with them. It is likely the most rigid setup for this, and would likely have the lowest runout as there are fewer interfaces.

The big pro right now for an MT3 end mill holder is that they are cheap. So you can take your time on the more expensive products like collets and holders.

Would something like this be exceptable? It's straight shank ed and if I am correct it's held with the 3 jawed chuck. I don't really understand how it's not a good idea to hold a end mill in a lathe chuck but ok to use something like this?

 

[markba633csi]

No, what you should use is a Morse taper collet with a drawbar
You take the chuck off and the collet slips into the spindle taper
You can buy MT collets individually and you can make a quickie drawbar out of threaded rod and a nut and washer
This assumes your chuck is fairly easy to remove-- some of the flange-type mounts are not so easy

 

[SouthernChap]

Gotcha! thanks!

Would something like this be exceptable? It's straight shank ed and if I am correct it's held with the 3 jawed chuck. I don't really understand how it's not a good idea to hold a end mill in a lathe chuck but ok to use something like this?

Well, if that product is designed to be used in a lathe's chuck, it might have a non-hardened shank so the hardened chuck jaws can grip it. If that's the case then it'll be safe to use at least but you'll be adding extra layers of inaccuracy if you used it.

Endmills aren't like drills that tend to have relatively soft shanks, their shanks are hardened and so the jaws can't get a decent grip on the endmill shank and this leads to a real possibility of the tool slipping; either rotationally, which can damage the tool shank and/or the chuck jaws, or laterally where the endmill can be pulled out of the chuck, damaging the workpiece or potentially, the user!

One of the reasons ER collets are so good for tool holding is that their design is such that they theoretically grip all the way along the shaft of the tool and give a better more precise and repeatable hold.

Your lathe spindle has an MT3 taper in it's bore so you can fit an MT3 collet with a drawbar (which as someone has said you can make yourself or buy) that runs through the spindle bore to the back and when tightened pulls the MT3 collet into the MT3 taper, keeping the collet in place and tightening the collet around the tool.

Or you could go with an ER collet chuck. One of these should fit on your spindle flange for example:

Collet Chuck, ER-32, 4" Diameter 4231

ER Collets & Collet Chucks 4231 ER-32 4" collet chuck; Mounts on 4" spindle flange or adapter; Shorter than standard 3-jaw chuck; Allows 25/32" stock ...

littlemachineshop.com

Obviously you'd need to buy collets but you can start off with just the collets you need for the tooling you have.

Here's a good and very recent video Quinn from Blondihacks did on collets generally, worth a watch:

You'll get away with using the setup you currently have a certain proportion of the time but the probability is, sooner or later something'll go wrong, and you'll be lucky to avoid damage to something.

 

[markba633csi]

Collets have better grip but they also have much less runout than a 3-jaw chuck

 

[steelcat]

Thanks for all the great info!
It's really appreciated guys!
I think the ER-32 collet chuck will be the way I go.

 

[homebrewed]

Thanks for all the great info!
It's really appreciated guys!
I think the ER-32 collet chuck will be the way I go.

ER style collet chucks are less problematic than MT3 collets for a couple of reasons.

The first is that MT style tapers are meant to be self-holding (to a point) so it's awfully easy to over-tighten them with a drawbar. I had a co-worker do that on a Sherline mill and it took some pretty good whacks with a hammer to free it. I was concerned about damaging the spindle bearings but there wasn't much of an alternative.

The second is that ER style collets have a wider range, in terms of what they can hold, diameter-wise; and they release more easily. Just make sure to keep the collets and collet nut clean, otherwise you may end up with excess runout.

 

[Smithdoor]

Both ER and Morse tapper are good.
The morse is lower cost.
One set of ER can be use on more that one machine tool and other uses.

Dave

 

[steelcat]

ER style collet chucks are less problematic than MT3 collets for a couple of reasons.

The first is that MT style tapers are meant to be self-holding (to a point) so it's awfully easy to over-tighten them with a drawbar. I had a co-worker do that on a Sherline mill and it took some pretty good whacks with a hammer to free it. I was concerned about damaging the spindle bearings but there wasn't much of an alternative.

The second is that ER style collets have a wider range, in terms of what they can hold, diameter-wise; and they release more easily. Just make sure to keep the collets and collet nut clean, otherwise you may end up with excess runo

ER style collet chucks are less problematic than MT3 collets for a couple of reasons.

The first is that MT style tapers are meant to be self-holding (to a point) so it's awfully easy to over-tighten them with a drawbar. I had a co-worker do that on a Sherline mill and it took some pretty good whacks with a hammer to free it. I was concerned about damaging the spindle bearings but there wasn't much of an alternative.

The second is that ER style collets have a wider range, in terms of what they can hold, diameter-wise; and they release more easily. Just make sure to keep the collets and collet nut clean, otherwise you may end up with excess runout.

I'm offended that you actually think that I would over tighten anything! LoL
You must be the proverbial fly on the wall in my shop.
I am very new to maching but it didn't take me very long to figgure out that a little piece of trash in the wrong place can bugger up the whole works. I keep my air pistol handy when working with my machines.
Nevertheless that's great advice!

 

[steelcat]

I just ordered a Er 32 collet chuck, full set of collets (wow they are pricey) and
hopefully a better vertical slide.