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HF Micro mill collets required?

3K views 13 replies 6 participants last post by  jrenyard 
#1 ·
I'm planning to get HF's Micro Mill.

The one critical job it will be doing is finishing one or more 60% 1911 frames.
The mill comes with a Jacobs style chuck.
Is this sufficient to run the small (.050) end mill I'll be using to cut the rails,
assuming light passes and fairly slow feeds?
I plan to cut them undersize and open them up with a rail file anyway.
I don't want to bother with collets and a drawbar right now if I don't need to.

Any experience with this?

Thanks,
Sam.
 
#3 ·
Hello Sam,
A small endmill bit makes a marginal groove for sliding components. Holding it in a Jacobs chuck makes it even worse. That is because the small end mill bit will tend to slide when held by the chuck's three edges. Usually the cutter will slide downward wrecking your work because cutters bite downward.

Besides a collet to hold a mill bit or arbor there are toolholders. Those have the taper of your mill's quill and use a set screw(s) to retain the tool. Keep the setscrews tight !!! They cost more than collets but can be easier to use and change for same-sized bits and arbors. They do take up a bit more Z axis space than collets. I think the HF micro-mill uses the R-8 taper tooling.

My little red HF mill-drill uses MT#2 taper tooling which is a PITA to keep changing. But the mill fits my laundry closet along with my 7x10 HF mini-lathe. Space is scarce even though I live in Arizona (NW valley area)!!!

I suggest using a small arbor and a small side cutter mill. Those look like a tiny saw blade (or "slitting saw"). Another type is a "Woodruff Key cutter" which has the small saw blade-like cutter as part of its' own shaft.

These things are used on a verticle mill from the side of the work hence the name "side cutters". They also run at lots slower RPM's or surface feet per minute. For the correct SFPM look up the parameters in Machinery's Handbook or similar reference text (or internet) for the material you plan to machine and the cutter diameter.

Places like ENCO or MSC or Little Machineshop have decent prices on small tooling for the home shop machinist.

VD
 
#4 ·
O.K. I'm convinced !

Hello Sam,
A small endmill bit makes a marginal groove for sliding components. Holding it in a Jacobs chuck makes it even worse. That is because the small end mill bit will tend to slide when held by the chuck's three edges. Usually the cutter will slide downward wrecking your work because cutters bite downward.

Besides a collet to hold a mill bit or arbor there are toolholders. Those have the taper of your mill's quill and use a set screw(s) to retain the tool. Keep the setscrews tight !!! They cost more than collets but can be easier to use and change for same-sized bits and arbors. They do take up a bit more Z axis space than collets. I think the HF micro-mill uses the R-8 taper tooling.

My little red HF mill-drill uses MT#2 taper tooling which is a PITA to keep changing. But the mill fits my laundry closet along with my 7x10 HF mini-lathe. Space is scarce even though I live in Arizona (NW valley area)!!!

I suggest using a small arbor and a small side cutter mill. Those look like a tiny saw blade (or "slitting saw"). Another type is a "Woodruff Key cutter" which has the small saw blade-like cutter as part of its' own shaft.

These things are used on a verticle mill from the side of the work hence the name "side cutters". They also run at lots slower RPM's or surface feet per minute. For the correct SFPM look up the parameters in Machinery's Handbook or similar reference text (or internet) for the material you plan to machine and the cutter diameter.

Places like ENCO or MSC or Little Machineshop have decent prices on small tooling for the home shop machinist.

VD
O.K. , Collets or tool holders it is. ( not cheap- lazy).
Thanks for both replies.
I've been searching for the Woodruff cutters, but can't find any in the right size except one site that offers them for truly hideous prices ( in gold yet!).
The Micro uses the MT2 taper also, but like you, space is an issue here too.
Maybe it's an AZ thing- I'm down here in Mesa.
I'll try a more diligent search and look for the side cutters too.

Thanks,
Sam.
 
#5 ·
Hello Sam,
The #2MT taper is a real PITA. They stick and are very tedious to release. The tang type can release by themselves when they are not supposed to. That taper is intended for drilling with simple down forces only. Sometimes a key slot is put in the quill to help remove the #2MT tooling with a steel wedge thing.

Due to the limited space under the quill of these little bench mills the user has little room for fancy tool changing solutions. A 1/4 inch tool holder or 3/8 inch tool holder will be a faster system to change for those shank sizes. The 3/8 inch size is popular and endmill shanks etc are common in that size with all sorts of cutter diameters. The smallest woodruff key cutters will have a shank size of 3/8 inch diameter.

There are econo tool suppliers on the internet. There are also local Phoenix area machine tool suppliers.

Another great resource is the Valley Metals Club (online yahoo group and active club meetings locally), a very helpful bunch of fellows and gun guys too.

VD
 
#6 ·
Do tool holders need a drawbar also?

Hello Sam,
The #2MT taper is a real PITA. They stick and are very tedious to release. The tang type can release by themselves when they are not supposed to. That taper is intended for drilling with simple down forces only. Sometimes a key slot is put in the quill to help remove the #2MT tooling with a steel wedge thing.

Due to the limited space under the quill of these little bench mills the user has little room for fancy tool changing solutions. A 1/4 inch tool holder or 3/8 inch tool holder will be a faster system to change for those shank sizes. The 3/8 inch size is popular and endmill shanks etc are common in that size with all sorts of cutter diameters. The smallest woodruff key cutters will have a shank size of 3/8 inch diameter.

There are econo tool suppliers on the internet. There are also local Phoenix area machine tool suppliers.

Another great resource is the Valley Metals Club (online yahoo group and active club meetings locally), a very helpful bunch of fellows and gun guys too.

VD
Do the tool holders you reference (esp. MT2) require a drawbar also, or are they retained in the quill differently?
Also,do you have any suggestions for locating small- i.e. .080 or less face width Woodruff cutters?
I've checked MSC, Enco, and Grainger, no luck.
Sam.
 
#7 ·
Sam,
Yes, the tool holders with the #2MT taper use a drawbar, otherwise they would work loose and fall out due to side loading.

I checked Grizzly and they don't have any thin key seaters or slitting saw blades.

A quick check of the Marshall Tool & Suppky Corp catalog shows a couple small woodruff keyseat cutters that measure 1/16 inch slotting. (602-269-6295) located 3114 W Thomas Rd, Suite 501, Phoenix, AZ 85017. My catalog is 15 years old so call them and ask. (They are the former Dewitt Tool and Garette Industrial Supply companies here in Phoenix)

My Production Tool Supply catalog is also out of date and out of town (Detroit area). Their showroom in Warren, MI was just down the road from my office at Army Headquarters years ago. It was a fun place to visit over a long lunch. They also show the thin (1/16 inch) woodruff key seaters.

There are thin slitting saw discs and arbors available under 1/8 inch thicknesses. They cost more than the key seaters and require an arbor to mount them.

Look for used-machinery-and-tooling shops both in the valley area and Tuscon for the best deals on this stuff. Big time difference in cost vs new. Another source is the tool sharpening shops that regrind cutters etc. They usually have lots of unclaimed cutters that are resharpened for sale.

Once while shopping a local scrap metal yard (Davis Salvage) I found a large pile of brand new ceramic tool inserts NIB !! I bought a couple small boxes of them as well as some used but useful carbide inserts for my shop. A few days later I checked the cost of those new ceramic inserts and about had a coronary !! I rushed back to the salvage yard with cash in hand to discover that those spendy inserts were all gone !!! The pile would have cost me perhaps a few hundred bux. The retail price was over one million dollars !!! It pays to shop.

VD
 
#8 ·
One last thing, get a 20% off coupon and get the mini-mill. It is so much more machine for not a lot of extra money. I hope that you plan on keeping it for a while, the table size alone it worth the extra money. I know that the micro-mill seems cheaper, but the R-8 collets are a standard that makes life easier.

Mark
 
#9 ·
Thanks for the info

One last thing, get a 20% off coupon and get the mini-mill. It is so much more machine for not a lot of extra money. I hope that you plan on keeping it for a while, the table size alone it worth the extra money. I know that the micro-mill seems cheaper, but the R-8 collets are a standard that makes life easier.

Mark
Thanks for all the good info, I appreciate you taking the time.
Now I have a good starting point.
I hadn't even thought of the coupon deal on the mini- I like the idea of more common tooling.
Again thanks, I'll keep you posted on my progress.

Sam.
 
#10 ·
Hello Sam,
I second Markp's suggestion. If at all possible go for the mill with the R-8 (Bridgeport) taper. Why ???? The #2MT really does suck !!!! It is problematic to change using a drawbar holding tooling in place. I have used both types (plus others). In fact I currently own both types of mill, ie a HF "big red" with the #2MT located in my apartment laundry closet shop and a Bridgeport head-equipped K&T Milwaukee at the new shop using the ever-popular/practical R-8 taper stuff.

Happy shopping !!!
VD
 
#11 ·
One more in support of the Mini-mill in R8 ( it also comes in MT - don't buy that!)

I have a big mill-drill, but I use the mini a lot more.
After that, you will be saving for a DRO. Trust me.

Go ahead and get a set of collets. enco has sets for cheap, and they have a 15% discount right now with a coupon code.

And when you buy the drills for the pin holes, buy the best you can find in those specific sizes.
I understand that if you use high-quality, sharp drills held in collets, you can get enough accuracy that you won't need to ream the holes.
 
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