Spindle adapter for drill press

[JScott]

In the latest delivery thread I just posted some pictures of the tools I found at the local big box store here in Colombia (see last attachment below).  The store is just over an hour drive away. (Driving in Colombia is a whole, separate thread!)  Got this drill press for the usual price for a 5 speed, Chinese, bench top model.  I probably don't really, really need a drill press but they are so handy and useful I just like having one around.  Since I'm retired I have more time to play around and this is going in my little shop.  I'm going to add items here and there as I find them.  Things like a bench grinder, bench vise, band saw, etc.

Now to get down to it.  I've been going through the old, back issues of Popular Mechanics from the late 40's and on up to the mid 50's so far.  I've done this before and really was amazed by the explosion of home workshop information that was fueled by the after effect of WWII.  It seems like everybody had some kind of home shop going on in their garage, basement or wherever.  They were working in wood, metal, glass, everything under the sun.  Building furniture, lamps, photography gadgets, you name it.  There are plans to make anything and everything including the machine tools such as  drills, scroll saws, table saws, die filers etc.  It also seems like many, many folks had a small lathe as well.

One of the things that is mentioned quite often is light milling with a drill press.  This would be a great feature for a drill press which brings me to the point of this thread.  The drill presses in use back then had the chuck mounted to the spindle/quill with a mechanical fastener such as a machine screw or bolt.  This allowed the drill to accept the side load imparted by the cutting action of an endmill say when facing or cutting a slot.  Today's drill press has the chuck mounted on a tapered nose so when any side load is added you better watch where you're standing because the chuck is going to leave rapidly.   All this is old news.   But........

Going through the old articles (you guessed it) there was one on milling with a drill press.  And this caught my eye.

   

It's a little gem called a spindle adapter; which you can mount if your drill press doesn't have a mechanical connector for the chuck. This one is apparently attached with a threaded collar.  So......., I thought to myself, why not add a spindle adapter to this drill press. Voila, light milling here we come!  Here is the data on my drill press and if my Spanish is up to the task it appears to have an MT2 taper on the spindle nose.  The nose isn't threaded but it could be drilled and tapped to hold the adapter with a screw like the chuck on a hand drill is mounted.
(Note: this manual is in Spanish and Portugese; very handy)  

       

I started digging for a spindle adapter for female MT2 going to a 1/2" bore.  No luck; on any size.  Well, if you can't get one...., make one (thanks Hawkeye).  After more digging I have come up with an idea to use a straight shank ER collet chuck reamed to an MT2 taper.  This would provide a stout attachment method and the ability to mount small end mills or a tiny fly cutter.

       

These ER collet chucks come in various diameters of straight shanks.  I just need to select one with enough "meat" and Bob's your uncle.  The chuck will be held to the spindle by a socket head capscrew of sufficient diameter, say, 3/8" or 10 mm.  From where I sit I think a C25 or C32 (25mm or 32mm shank) with a 10mm bore would be a good starting point.  They come in shaft lengths from 50mm up to 200mm.  I think 50 might be little short but cutting down a longer one to keep it shorter and more rigid is doable.

Well, there it is.  Maybe there is already something readily available out there and any info anyone can provide would be appreciated.

So, I'm looking for input and ideas before I start ordering parts and pieces.  I need to find out more about the dimensions inside the collet chuck to see if there is room for a socket head cap screw and if there is enough material to provide a shoulder for the screw head, etc.

Thanks for listening and more to come.
JScott

[vtsteam]

You probably will want to knock that drill chuck off and check the spindle taper for actual dimensions before deciding what adapter to order, and what size retaining screw you want to use.

I'm surprised at the MT2 male tapered spindle -- I have a similar 8" bench drill and it has a Jacobs JT33 taper. Other drill presses are usually a female MT taper and then you use an MT male to JT male adapter (tang type) to mount a JT drill chuck.

[JScott]

I did some measuring and it turns out the spindle  taper is a "short" version of MT2 that is designated B16. I found several adapters on eBay that go from B16 to ER collet. I'll probably go to an ER-25. You can get collet sets that go from 1/8 to 5/8 inch or 1 to 16 millimeter.

[vtsteam]

JScott, great. You'll probably only really need 3/8" max shank for milling. The actual end mill size will probably be smaller than even that, though 3/8" is a common shank size.

Now you'll still have to retain your adapter to the spindle for milling. There may not be a way to put a retaining screw inside the adapter. You might also consider making a retaining collar to fit on the outside of the spindle and the adapter.

My drill is probably different than yours, so I have no idea what is available for gripping above the tapered end of your spindle. But if there's enough spindle exposed, then the ER adapter could have a flat put on the shank end. Then enclose the shank inside of a close fitting collar retaining it with a set screw.

If the collar is made long enough and bored at the other end to fit the spindle, perhaps you can use the same method of using a flat on the spindle and setscrew there. Your ability to do that would depend on how much length beyond the bearing the spindle protrudes. If not enough maybe you could come up with another method for that end.

[vtsteam]

I just checked my drill which looks very similar to yours, except it's a Delta, and as I said has a JT33 mount for the chuck. Unfortunately there is almost no space to mount a collar on the spindle. If yours is the same, let's hope you can find a way to add a screw to your ER to MT adapter.

If I were to modify my press to take end mills, I'd probably take the spindle out entirely, cut off the external tapered piece, then through drill 3/8". Then open the business end out to full MT2 taper.

I would then get a 3/8 MT2 collet to hold 3/8" shank end mills. Little Machine shop has them - maybe Ebay as well. I'd use a length of 3/8-16 all thread with a couple jam nuts and washer on the end to secure the collet - or make up a proper drawbar.

I'd also get an MT2 to drill chuck adapter (in my case MT2 to JT33) so I could mount the drill chuck again. Now you can also mount a lot of MT2 accessories, as well.

We haven't addressed any of the stiffness issues of these small drill presses when used as a mill -- but the result may be quite limited in capability. Still, if you're doing model work, and you have no other mill it's bound to be better than nothing.

If you have a lathe, a milling attachment for that, and/or a milling and boring arbor will probably have more capacity and give more precision and better finish.

Nevertheless doing a drill conversion does add versatility to a modest shop, and also the challenges of making tooling and getting the most out of limited capabilities is a large part of the fun of home metal shop work.

I have a mill already, but your project has made me think about modifying my drill anyway, just for the above reason.

[JScott]

Sorry for the delay but we've been pretty busy this year. I'm starting up this thread again with my proposed solution to build a small, light duty hobby mill. After some research I found that there is an adapter available for the B16 (MR2) taper on my drill press spindle. They are make a collet chuck in sizes from ER11 to ER40. I picked the ER25 collet chuck based on price and size. Here's what they look like. 

   

My plan now is to mount this chuck on the spindle and then cross drill them both for a 0.25 inch diameter roll pin. This should be sturdy enough to allow milling side pressure without flying apart. More details to follow.