Thread: BF-20 Mill Questions Fitting a Collet Chuck

Anyone have this mill from H&F?

https://www.machineryhouse.com.au/m650

The spindle taper is 3MT but drawbar has an M10 thread. I'm wanting to fit a collet chuck...

So questions:

1) Can you get away with some kind of M10/M12 adapter?
2) Or best to machine a new drawbar?

Mainly because I've only seen one or two 3MT / M10 collet chucks around. I'm looking at an ER32 chuck/collets.

Probably just as easy to make a new drawbar. They are pretty simple things to make.

Simon

Sent from my SM-G900I using Tapatalk

I had an ER25 collet chuck on an X2 mill, the bolt was 10 mm but only went in about 4-5 mm. It eventually stripped the thread on the bolt and damaged the thread in the collet, so I went to fix it, and found that there was an insert adapter threaded into it, which was 12 mm.
So you could get a 12 mm bolt cut off about 20+ mm of thread and drill and tap it to 10 mm, just make sure that you have ample thread to hold the drawbar.
Hope this helps.
Kryn

Can it not be had in R8?

When I bought my first mill, as an ingenue I opted for the MT3 taper thinking it would serve some benefit in tool changing between it and a future lathe purchase. Ended up with a lathe built around MT2 tapers, while being driven up the bloody wall having to knock out MT3 taper tooling on the mill, and had no desire to swap tooling between the two anyway.

If I had my time again I would have chosen R8.

Originally Posted by Precious Mettle

Can it not be had in R8?

When I bought my first mill, as an ingenue I opted for the MT3 taper thinking it would serve some benefit in tool changing between it and a future lathe purchase. Ended up with a lathe built around MT2 tapers, while being driven up the bloody wall having to knock out MT3 taper tooling on the mill, and had no desire to swap tooling between the two anyway.

If I had my time again I would have chosen R8.

I have only seen MT 1 2 3 4 type holders and know nothing about other types of tapers.

Why do you prefer R8 ?

Bill

Hi Bill,

My current mill has a MT4 and my new to me replacement mill has iso40. While at the time I was happy with MT4, I have grown to loathe a MT on a mill because you have to belt the crap out of the drawbar to release the tool from the taper. Not particularly good for the spindle bearings, eventhough they are not a precision bearing on these type of mills. I'm not familiar with R8 but I do believe they are a self releasing collet same as ISO (INT) 30, 40 & 50 tapers. This means that the tooling literally falls out once you loosen the drawbar. The taper is merely used to seat the tool in a precise location and not used to drive the tool. The rotational force comes from lugs that engage the tool under the taper. A much better system.

Cheers,

Simon

It's self releasing

That is not correct for NT tapers they hold after the drawbar is released and require a bang on the draw bar to release . If it just falls out after the drawbar is loosened it was never in properly and or too much oil or garbage on it . What you have been watching most likely is power drawbars that push the tooling out automatically .

Originally Posted by bpbuilder

Anyone have this mill from H&F?

https://www.machineryhouse.com.au/m650

The spindle taper is 3MT but drawbar has an M10 thread. I'm wanting to fit a collet chuck...

So questions:

1) Can you get away with some kind of M10/M12 adapter?
2) Or best to machine a new drawbar?

Mainly because I've only seen one or two 3MT / M10 collet chucks around. I'm looking at an ER32 chuck/collets.

Hi, My BF20 clone, MT3 taper came with an M12 self releasing drawbar. I've not had any problems with getting the taper to release properly. I do take very good care to make sure that both the socket and the mating tool holder are clean, and I do wipe both with an oiled paper towel. A plastic wine cork with a paper towel wrapped around it, makes a very good cleaning tool. Also I made a small square socket key with a fixed 100 mm long handle to tighten and loosen the drawbar, it takes very little force to eject the taper.

An ER32 collet holder also gives me about 35 mm extra headroom compared to the one originally supplied with the mill. Useful when using the RT and three jaw chuck.

HTH.

Thanks all.

The manual talks of an M10 thread on the drawbar but I've checked the actual thread on it today and funny thing is that it's neither and M10 or M12! Nor does it match anything imperial so I'm stuffed anyway! Not sure what on earth went wrong in the factory when this was built. It's close to an M12 but with a 12TPI thread...

I'm either going make a new draw bar up or request a replacement that has a standard thread.

To answer some other questions.

Yes can be had in R8, but I already have the mill in 3MT. And it was more accessible to buy in this version locally so I went with it. As mentioned above I don't have to knock it out anyway so 3MT doesn't bother me. There is some debate over which is better (R8 or 3MT). What I have works for me.

It's easy enough to get out by following the given instructions i.e. loosening the drawbar from the top and holding counter bearing, which forces the tool mostly out without it dropping completely out.

At 12 TPI it is probably 1/2" Whitworth. NOT 1/2" UNC

Roger

Originally Posted by rogerbaker

At 12 TPI it is probably 1/2" Whitworth. NOT 1/2" UNC

Still wouldn't accept it as the major diameter is approximately 6% out.

A number of people have mentioned having a 1/2" Whitworth thread on their drawbars. I think it is a poor choice myself. My mill came with an M14 threaded drawbar which is just as bad. I have made up an M12 and an M16 drawbar. I just used some steel rod and welded a length of thread onto it. The nut end is an M10 nut welded on, but I drilled it out and turned the end of the drawbar to fit. I then fitted a thick washer under the nut before welding the end.

Most MT3 tooling will have an M12 thread. It would be easier to try and stick with the one size.

Dean

Originally Posted by Oldneweng

A number of people have mentioned having a 1/2" Whitworth thread on their drawbars. I think it is a poor choice myself. My mill came with an M14 threaded drawbar which is just as bad. I have made up an M12 and an M16 drawbar. I just used some steel rod and welded a length of thread onto it. The nut end is an M10 nut welded on, but I drilled it out and turned the end of the drawbar to fit. I then fitted a thick washer under the nut before welding the end.

Most MT3 tooling will have an M12 thread. It would be easier to try and stick with the one size.

Dean

Yeah I agree with that 3MT/M12 is much easier to find.

I'm still not convinced it's within tolerance for a 1/2" BSW thread though at least not to BS84 or BS1083.

In what way do you think it is not in tolerance for a 1/2" Whit thread? Due to the rounded thread tips the size is somewhat less than 1/2". I recall a US YouTuber saying he had found this weird thread size. He measured it at 12 tpi and 31/64". He had no idea what it was.

Dean