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View Full Version : New powered drawbar project for mill just finished...



BobWarfield
12-17-2006, 07:29 PM
Guys, if you don't have one of these, you should look into one. They are the greatest thing since sliced bread. Very easy to build, and mine works extremely well. I hate to sound like an advertisement, but I was just so tickled at how nice it is for no more trouble than it was to build!

Here are a couple pix of the finished result:

http://www.thewarfields.com/img/Toys/MachineTools/MillStuff/PowerDrawbar/PC173693.JPG

http://www.thewarfields.com/img/Toys/MachineTools/MillStuff/PowerDrawbar/PC173694.JPG

To operate, press the side of the lever marked "OUT" and the tool will drop into your hand in 2 or 3 seconds. Insert a new tool in the spindle, press "IN", and it torques it down again in another 2 or 3 seconds.

There is a little movie of it on my web page:

http://www.thewarfields.com/MT/CCMillDrawbar.html

This is based on Joe Vicar's plan set, which are cheap and worked out really well for me:

http://home.insightbb.com/~joevicar3/cheap_drawbar.htm

The impact wrench you'd need was on sale at Harbor Freight not long ago, but I don't know if they still are. This would be an easy project to get running between Xmas and New Year's.

Cheers,

BW

JPR
12-17-2006, 08:51 PM
nice work BW, that has been on the to do list.

wierdscience
12-17-2006, 09:09 PM
Looks good,nice looking job,what did you use for the switch?Was it an off the shelf number,or a one-off of your own design?

So does it actuate the air cylinder and the butterfly wrench in the same motion?

I'm wondering if I could do similar,but instead of the air cylinder just mount it solid,but borrow the idea of moving the quill up from the Tormach design.In other words,mount the air wrench so the socket doesn't grab the drawbar hex unless you move the quill up into it and then hit the button?

Anyway anything would be better than the wrench method.

torker
12-17-2006, 09:58 PM
Bob...very cool gadget! Looks like good use of the KISS principle :D
Russ

BobWarfield
12-18-2006, 12:28 AM
Looks good,nice looking job,what did you use for the switch?Was it an off the shelf number,or a one-off of your own design?

So does it actuate the air cylinder and the butterfly wrench in the same motion?

I'm wondering if I could do similar,but instead of the air cylinder just mount it solid,but borrow the idea of moving the quill up from the Tormach design.In other words,mount the air wrench so the socket doesn't grab the drawbar hex unless you move the quill up into it and then hit the button?

Anyway anything would be better than the wrench method.

I got the plans from Joe Vicar:

www.HomeShopAccessories.com

This is the one labeled "2006 Power Drawbar Improved". Very nice design. The plans are very well done, and there is good narrative text and photos as well.

The valve activates the impact wrench and the air cylinder all at once.

There are a couple of ways to simplify the design further, and make the step of engaging the impact wrench manual. You could do so with the quill, but I know that personally I would be sure to fire up the mill with the darned thing annoyed and be picking pieces of socket out of my teeth.

You could also just put it on spring loaded rods with a handle to pull it down. The trick will be to engineer a motorcycle throttle like grip that let's you twist to rotate the impact wrench either direction.

This approach is so simple though, and the air cylinder with the impact wrench only cost about $50, that I would recommend just going with the plans. It really comes out slick. I showed it to a machinist buddy that came over for dinner, and he walked out starry eyed and shaking his head.

When you consider what commercial drawbars cost, even the "Aussie" drawbars advertised on ebay, this is quite a bargain.

Best,

BW

SJorgensen
12-18-2006, 02:00 AM
It makes me appreciate the simplicity of my Kwik Switch tooling.

Although I do appreciate the ingeniousness, and the skill and the quality that is shown in this project.

smagovic
12-18-2006, 07:07 AM
Bob, great job!! I am making copies of all your pictures. I just got my driver. They are still available, we just have to select 3/8". For some reasons this one just does not come automatically when asking for the drivers (only 1/2" shows - price is changing though). Many thanks for the discovery and for the pictures. Makes it easier. Vic

Mcgyver
12-18-2006, 07:45 AM
nice work Bob, two Q's, does the actuator bring it into position before it starts spinning? Secondly, on my R8 it takes a couple taps with mallet to loosen the tooling after loosening the drawbar, is that not required here because the impact wrench creates enough vibration to do it?

Wirecutter
12-18-2006, 10:45 AM
Secondly, on my R8 it takes a couple taps with mallet to loosen the tooling after loosening the drawbar, is that not required here because the impact wrench creates enough vibration to do it?
That is slick, like Mcgyver said. I'm also curious about using it on the Bridgy R8. My mill's "standard excessories" include one of those ratcheting box-end wrenches - a 3/4" for the drawbar. It sits on one of the bolts that secure the ram pivot so it's always handy. Then of course there's the rawhide mallet that has a little resting place on top of the ram - used for whacking the drawbar without boogering up the top of it.

http://i70.photobucket.com/albums/i106/wires99/shop/wrench_n_mallet.jpg
-Mark

BobWarfield
12-18-2006, 11:10 AM
Vic, you'll want to order this fellow's plans--they'll save you a lot of trouble trying to figure out my pictures, not to mention his pictures and plans better show some important details I don't think I'd have guessed too easily. I have not and will not show all the details to do it without the plans as I don't think that would be right.

RE drawbar whacking (gee, that didn't sound right!), the force applied by the air cylinder seems to be adequate so that it isn't needed. I suspect the knocking of the impact wrench also contributes. Those of you who've fooled with impact wrenches know they're great at working stubborn fasteners loose (or shearing them off too I suppose). I've had a number of mill holdres in and out with no hiccups at all. Just amazing how fast it works.

There is no delay between the cylinder and wrench, but the engagement happens quickly and smoothly. There are some interesting things called out in the plans that I believe contribute to this, but again, I will say no more as it wouldn't be fair to Joe Vicar.

I will be monitoring whether there is any undue wear on the drawbar. There hasn't been so far. I was told by someone who built a full automatic toolchanger around one of these that he decided to harden his drawbar without annealing it. Before doing so he also polished the threads. I had the impression this was more helpful in his ATC application than in a manual application, but I suppose it would be something to consider if you think your drawbar is getting beat up. As I say, I have seen no sign of trouble, but just started using it.

It's definitely been one of my top tooling projects so far.

Best,

BW

smagovic
12-18-2006, 02:41 PM
Bob, I got the drawings when you first time mentioned it. It took so long to get the driver from the FH. That guy is really nice. I could not find the first set of the drawings he sent me so I call him, and he sent me another one. Thanks. Vic

Cecil Walker
12-18-2006, 02:42 PM
Good job Bob, another one for the "to do" list.

japcas
12-18-2006, 07:58 PM
Yes, nice looking work Bob. I ordered my set this morning and when I came in this evening I had an email waiting with the plans attached. That's the cool thing about ordering stuff like this from the net. Same day delivery.:) I'll be gathering parts soon as it looks like a lot of bang for the buck compared to some other mods. Thanks for sharing.

BobWarfield
12-19-2006, 11:28 AM
I'll be gathering parts soon as it looks like a lot of bang for the buck compared to some other mods. Thanks for sharing.

It's right up there with my all time best labor saving mods:

- Power feed for mill X-axis.

- Power drawbar for mill.

- QCTP for lathe.

- Variable speed DC motor for lathe.

- DRO

Each one of these has made me more productive in the shop, which is important, since I'm pretty slow even on a good day!

Unfortunately people keep asking over and over again, "Aren't you going to make anything with all these tools?" Somehow making tools doesn't count.

I know you guys probably hear that too!

Best,

BW

sid pileski
12-19-2006, 02:01 PM
Air powered, manual down feed for a Bridgeport style. It saves a lot of time, and I can't reach the top of my mill easily, so a necessity for me.

Sid
http://img.photobucket.com/albums/v108/sids32/P3220101.jpg
http://img.photobucket.com/albums/v108/sids32/P3220100.jpg

lazlo
12-19-2006, 05:12 PM
Nice job Bob!


I will be monitoring whether there is any undue wear on the drawbar. There hasn't been so far.
...
but I suppose it would be something to consider if you think your drawbar is getting beat up.

Personally, I wouldn't worry about the impact wrench damaging the drawbar -- they cost $20 at MSC, Enco et al. But I'd keep an eye on the collet threads: that impact wrench is hammering the drawbar around 17 times per second with 75 ft lbs of torque, and most Asian collets don't have hardened threads.

Looks like a fun project!

Robert

BobWarfield
12-19-2006, 09:42 PM
Sid, thanks for posting. I have had a lot of people ask me how to do it without the air cylinder, but I had never actually seen one done. Very nice! That's a big ole mill, eh?

Lazlo, I'll keep an eye out on the whole works. Have yet to use an R8 collet in this mill (mill holders and an ER32 collet chuck), but the threads on the other R8 shanks may be susceptible as well.

I have to admit, the little air cylinder worked real well. I will also be on the lookout for other opportunities to fiddle with such things in the shop. Pneumatics are pretty cool.

Best,

BW