Please explain the Difference between Power Drawbar and Q/C

[fireguy976]

Hi,

just purchased a series one BP mill, I guess one of the older unit, as it has the 3/4 fixed speed motor and stepped pulleys.

I am taking time to get it set up, and after doing some research I would like to know more about ease of tool changes.

Ive seen videos of impact type wrenchs attached to the top that loosen the drawbar, elimenating the use of the wrench. This still requires the use of the threaded drawbar type tool holders.

Ive seen other types of "quick changers" on a bench type mill that uses a type of compression washer and a piston with lever action which simply pushes down on the bar to release pressure on the collet type holder and the tools drop right out in your hand.
This sytem seems the slickest of the bunch.

so hoping someone out here can shed some light on the differences for me and point me in the right direction to learn more about these, and what can be used on a BP mill.

Thanks,
Ken J

[LeeWay]

The QC type tool holders or Tormach style are set already for the length of your end mils. They will always be the same length when tightened into either a manual other type drawbar.
It makes no difference whether it is impact style or air actuator. I actually use a butterfly impact manually on mine with Tormach tooling. It's an R8 spindle.
Where this saves me time is even when I break an end mill, I can set another new one using my height guage and then continue milling from the last known good spot. No resetting of zero for the Z. Especially useful if doing work where the original surface is already milled away.

Power drawbars and quick change tool holders are two different things of course.
I only have a few of the endmill holders from Tormach, but they sure make life much easier.
I was working on an air cylinder drawbar, but it didn't work for my initial prototype. It wouldn't hold the QCTH tight enough when milling steel.
My newer design is with two of these cylinders. Should have p[lenty of oomph then.

[HimyKabibble]

Originally Posted by fireguy976 Hi, just purchased a series one BP mill, I guess one of the older unit, as it has the 3/4 fixed speed motor and stepped pulleys. I am taking time to get it set up, and after doing some research I would like to know more about ease of tool changes. Ive seen videos of impact type wrenchs attached to the top that loosen the drawbar, elimenating the use of the wrench. This still requires the use of the threaded drawbar type tool holders. Ive seen other types of "quick changers" on a bench type mill that uses a type of compression washer and a piston with lever action which simply pushes down on the bar to release pressure on the collet type holder and the tools drop right out in your hand. This sytem seems the slickest of the bunch. so hoping someone out here can shed some light on the differences for me and point me in the right direction to learn more about these, and what can be used on a BP mill. Thanks, Ken J

Ken,

The ones with the impact wrench work exactly like the drawbar, only without you having to do anything but turn on the air supply that jams the impact wrench down on the drawbar, and spins the drawbar out. The other kind inserts heavy spring washers between the head of the drawbar bolt and the spindle, so the spring washers provide the force to retain the collet. To release, you just need an air cylinder that comes down and, usually through a lever arm, pushes down on the head of the drawbar, compressing the spring washers, and releasing the collet.

Either of these can be built for about $40 in parts (most people use a $20 "butterfly" impact wrench from Harbor Freight for the first kind). I kinda like the second kind for its elegant simplicity. But, you need some hefty spring washers, and I suspect you might need something to prevent the whole quill from moving down when you compress the spring washers.

Combine either of the above with some Tormach tool holders, and you can change tools in about 2 seconds flat, and have precisely known tool lengths. Next best thing to an automated tool changer.

Regards,
Ray L.

[fireguy976]

Thanks Ray and Lee for the reply,

still very much learning here, huge learning curve.

So the tormach is a "unique" tool holding system, that allows quick in and out tool changing. So does that mean it has some sort of base collet type system, and when the pressure is releaved the tool drops out and then the new tool is held in place when pressure is reapplied?

And all that is independent of which draw bar system you use, either butterfly wrench or the air cylinder with the cupped washers????

Does it sound like i have some sort of grasp? or am I holding onto my own tool in hand here??

The air wrench system (or the cylinder with wahers) just allows easier changing of the threaded standard pieces that we all start with, which still means swapping out threaded collets and threaded drill chucks and fly cutters etc.

Im guessing here the tormach system is not cheap, and are all the tool holding bits and pieces proprietary? or are there clones of this out there?

Pics would help my visual type of noggin here very much.

Thanks again,

Ken J

[HimyKabibble]

Originally Posted by fireguy976 Thanks Ray and Lee for the reply, still very much learning here, huge learning curve. So the tormach is a "unique" tool holding system, that allows quick in and out tool changing. So does that mean it has some sort of base collet type system, and when the pressure is releaved the tool drops out and then the new tool is held in place when pressure is reapplied? And all that is independent of which draw bar system you use, either butterfly wrench or the air cylinder with the cupped washers???? Does it sound like i have some sort of grasp? or am I holding onto my own tool in hand here?? The air wrench system (or the cylinder with wahers) just allows easier changing of the threaded standard pieces that we all start with, which still means swapping out threaded collets and threaded drill chucks and fly cutters etc. Im guessing here the tormach system is not cheap, and are all the tool holding bits and pieces proprietary? or are there clones of this out there? Pics would help my visual type of noggin here very much. Thanks again, Ken J

Ken,

The Tormach system uses a modified R8 collet, and special holders that, unlike normal R8 tools, go back into the spindle with VERY precise repeatability of the Z position. All the details are on the Tormach site:

http://www.tormach.com/Product_TTS.html

They're really not terribly expensive. I think they're well worth the money. It's also not terribly difficult to make your own:

Hoss 16 Tool Automatic Tool Changer

Regards,
Ray L.

[Crevice Reamer]

Hi Ken! I think you've got it.

You may not have to buy a full set.

The Tormach system is not too expensive if you use same shank size end mills. Then you need only buy a few end mill holders and maybe some drill chuck holders.

But if you predominantly use collets--THEN it starts to get expensive.

Here's a pic of a few:

CR.

[fireguy976]

Thanks for everyones replys,

Ive got it figured out.

I can now see why alot of the Bridgeport users go to the impact wrench style of power draw bar.

Reason I say this is my machine came with a few bits of tooling, collets and such, but also a fairly large size fly cutter with 3 carbide inserts. It being a R8 style threaded insert, needs to be drawn up tight by the draw bar.
The quick change system would only benefit when the 3/4" collet can be left in place with use of the "stubby" tool holders.

The reason I say that is after reading about the automatic change system, the tension on the collet and the tooling is such that it needs to be set right, ie.. hand tight plus a turn for example. And if its necessary to change from 3/4 collet to fly cutter (or other large tool) it could be a pain having to precisely re adjust everytime.

I guess it comes down to how large a tool the operator is ever going to use or need to use,,, and can it be made, or safely be used in a 3/4" collet?

If tooling requirements are such that you are going to be using R8 shank items on a regular basis, then the power draw bar is the way to go.


If I have got this screwed up please chime in. You individual and collective experience is VERY much appreciated here. If can even call me grasshopper if you wish.........LOL

Thanks again,
Ken J

[Crevice Reamer]

Well, you still want the power drawbar, even WITH the QC system. Now, if you HAVE the power drawbar, AND the QC system, you are onlly a table-tool rack and some Mach3 setup away from a passive Automatic Tool Changer.

Maybe you can find (or make) a straight shank fly cutter that will fit into a QC end mill holder.

CR.

[HimyKabibble]

Originally Posted by fireguy976 Thanks for everyones replys, Ive got it figured out. I can now see why alot of the Bridgeport users go to the impact wrench style of power draw bar. Reason I say this is my machine came with a few bits of tooling, collets and such, but also a fairly large size fly cutter with 3 carbide inserts. It being a R8 style threaded insert, needs to be drawn up tight by the draw bar. The quick change system would only benefit when the 3/4" collet can be left in place with use of the "stubby" tool holders. The reason I say that is after reading about the automatic change system, the tension on the collet and the tooling is such that it needs to be set right, ie.. hand tight plus a turn for example. And if its necessary to change from 3/4 collet to fly cutter (or other large tool) it could be a pain having to precisely re adjust everytime. I guess it comes down to how large a tool the operator is ever going to use or need to use,,, and can it be made, or safely be used in a 3/4" collet? If tooling requirements are such that you are going to be using R8 shank items on a regular basis, then the power draw bar is the way to go. If I have got this screwed up please chime in. You individual and collective experience is VERY much appreciated here. If can even call me grasshopper if you wish.........LOL Thanks again, Ken J

Ken,

Drill chucks, flycutters, face mills, boring heads, etc. - all available, and work just fine, with a 3/4" straight shank. In fact, most of them have removeable shanks, and new shanks are about $20 each. I use a 4" flycutter with a straight shank - no problems whatsoever, even taking a heavy cut on steel. The Tormach collet is exactly like a normal 3/4" R8 collet, except with the face milled off. It will accept any tool any other 3/4" collet will accept.

Either the air ratchet or spring washer approach will both work fine. It's just a matter of personal preference. The advantage of the Tormach approach is you *can* make an auto tool changer later on if you want. That's not really practical with R8.

Regards,
Ray L.

[fireguy976]

Thanks Ray,

has anyone done a quick change for a Bridgeport yet? (the automatic tormach style)

with my BP mill do I need to change out the drawbar to go to the quick change system ie Mr Hoss's nifty system?

The drawbar sticks up about 5 inches, then there is the issues of the brake, and the clutch lever for the back gear, and the round shape of the upper section. So mounting would have to be with a base plate on the top.

Cheers,
KJ

[HimyKabibble]

Originally Posted by fireguy976 Thanks Ray, has anyone done a quick change for a Bridgeport yet? (the automatic tormach style) with my BP mill do I need to change out the drawbar to go to the quick change system ie Mr Hoss's nifty system? The drawbar sticks up about 5 inches, then there is the issues of the brake, and the clutch lever for the back gear, and the round shape of the upper section. So mounting would have to be with a base plate on the top. Cheers, KJ

Certainly lots of people have done the air ratchet type on BPs. I can't recall off-hand seeing the other kind, but I see no reason it couldn't be done. It's the approach I plan to take when I do mine. The spring washers would have to be small enough diameter to fit inside the quill bore, so no larger than the minor diameter of the quill splines. Since the quill would, presumably, be CNC'd, the downforce of the QC should not be an issue, and returning the quill to the full up position should put it in the right place. I just like the simplicity of that approach.

If you're just interested in quick tool changes on a manual machine, then I'd probably just spend the $150 to buy the air ratchet one on E-Bay.

Regards,
Ray L.

[fireguy976]

Thanks again Ray,

I asked mr?? Hoss about his system, because of the simplicity as you mentioned, and his concern as you mentined was the movement of the quill.

I wasnt sure exactly what you were referring to with regard to the movement issue until it was explained to me again slightly different,,,,, then the light went on. I did mention learning curve I hope.

Somehow the Mach 1 system may have addressed this issue, but with the prices quoted on the site, Ill be going with the impact wrench for now.

Is the design you mentioned with the internals similar to the Mach 1?

Great to learn form other BP owners like yourself.

Cheers,
KJ