Drill bit slipping in DA 200 collet (same used in Hurricane drill)

So I made a drill holder earlier this year out of an old Kennametal DA200 collet chuck extension. I'm not a fan of the DA style collets, I much prefer the ER style collets at work (I'm a machinist), but I figured that if it worked for John Middendorf it should work for me! As far as I can tell, John Middendorf and Tim Martin used the DA200 size collets in their Hurricane hand drill, so that's what I chose to use.

The issue I'm having is that my drill bits are slipping back in the collet until they seat against the end of the bore in the collet chuck extension. At that point they seem to be holding well enough (radially) to get some drilling done, but with much less of the drill bit sticking out than I intended. I'm using high speed steel drill bits and practicing on a big chunk of granite I purchased from the local landscaping stone place.

My question is, has anyone else had a problem with drill bits slipping in their Hurricane Mountain Works Rock Drill? If so, I'll make another drill holder from an ER collet chuck extension.

I use the ER style as well at work (industrial hand tool drilling).  It only slips if it’s not tightened enough YMMV as some people have greater strength than others,  a trick I use is to put a spacer in the back of the collet like a dowel pin or small bolt a tad smaller than the bit,  this will prevent slippage of the bit

In the Hurricane the drill bit isn't held afloat by the collet, the bit sits on the drill under the collet. Works great but I doubt it would work if you didn't have the bit riding against the drill under the collet. See if you can figure out a spacer like IcePick suggested.

IcePick wrote:

I use the ER style as well at work (industrial hand tool drilling).  It only slips if it’s not tightened enough YMMV as some people have greater strength than others,  a trick I use is to put a spacer in the back of the collet like a dowel pin or small bolt a tad smaller than the bit,  this will prevent slippage of the bit

Yeah, at work I tighten the bejeezus out of my ER collet nuts because if a tool slips it ruins very expensive work. I hadn't thought of the dowel pin trick because the drill bits I'm using pass totally through the collet, that is there is no dead space, but thanks for reminding me of the trick! I used that same trick on an old lathe I had with a large Jacobs Rubber Flex chuck when I would chuck up real short stock.

(Edit: I see I misunderstood your suggestion, Greg's photo clarified what you meant)

I may just make an ER collet drill holder anyway since I know the bit won't slip. Or, since I'm using high speed drill bits, I may make "disposable" drill holders with long taper collets in a simple hex stock holder, or heat shrink drills into a simple hex stock holder. I'm only planning on drilling a few bolt holes at a time for obscure route belays and rappels, and as long as I don't break the drill bit I can regrind them when I get home.

Greg Barnes wrote:

In the Hurricane the drill bit isn't held afloat by the collet, the bit sits on the drill under the collet. Works great but I doubt it would work if you didn't have the bit riding against the drill under the collet. See if you can figure out a spacer like IcePick suggested.

Thanks for the photo Greg! That pretty much answers my question. Middendorf and Martin must have had the same issue and designed their drill so that the back end of the bit was supported by the drill. I'll see if I can add a spacer to my drill to perform the same job.

You mentioned HSS bits.  Wouldn’t it be better to use masonry bits for stone ?   I don’t drill rock but would think HSS would dull quickly. 

IcePick wrote:

You mentioned HSS bits.  Wouldn’t it be better to use masonry bits for stone ?   I don’t drill rock but would think HSS would dull quickly. 

There are pros and cons to each style of bit. I decided to start with high speed steel bits that I ground to have a chisel edge, because I can get the bits very cheaply and I can regrind them easily, even while out at the crag. I'm sure the carbide masonry bits work very well, and I may eventually move to using those, but it was easier and cheaper for me to start with HSS.