X2 Electric-*Hydraulic* drawbar

[SScnc]

Hey guys,

This is an idea I had and had to try it out...

This uses the electric actuator from SurplusCenter seen in my other video but here it is used to push a piston into one cylinder and force the piston of the drawbar cylinder down to release the TTS style collets. The hose is for an icemaker and is expanding, once a real hydraulic hose is used the action will be much faster.

This keeps all the actuator and levers off of the mill head and mounts it remotely. This is just a quick "mock up" I threw together to test the idea and my cylinders out and will be refined later.

The electric actuator can of course be replaced with an air cylinder and any levers and limit switches needed.

YouTube- X2 Electric-Hydraulic drawbar

YouTube- X2 Electric-Hydraulic drawbar

[pete from TN]

Looks like it will work fine, did you make those cylinders or buy them? I am thinking that while it is really cool and obviously works fine you were doing fine before with just the electronics setup....? I have recently had a new idea that I am kinda working on to make a power drawbar with the same linear actuator. I will post here information once I have a working prototype. I am hoping this idea will allow for a MUCH higher drawbar pressure and yet not need any expensive or complicated apparatus to make it work. I am inspired tho by your ideas here and you are doing a great job.... peace

[SScnc]

Hi Pete,

Since I didn't have anything even close to suitable laying around I made the cylinders from some 2" round bar and the pistons from a 1" round bar, turned on my 9x20 HF lathe. While it was working fine before, I wanted to reduce the bulk on the mill head and also, I don't need to use any levers with this setup, the actuator pushes directly onto the piston rod and so that cycle time is reduced.

I also wanted to add more Bellevilles to the drawbar anyway. The drawbar cylinder will be turned 180* so the hose outlet is on the backside.

But mainly, I just had to try it Thanks for the nice words, I have been inspired by others on here too. I'm looking forward to seeing what you develop for yours, sounds very interesting.

Later

[HimyKabibble]

Nice! VMCs often use a similar approach, using a low-pressure (100PSI) pneumatic cylinder with a long-ish travel to push a small daimeter hydraulic cylinder to generate high hydraulic pressure (1000PSI or more), which then moves a large-diameter, short-travel hydraulic cylinder to compress the drawbar.

Another approach I'm pursuing, that I haven't seen anyone do yet, is using a gearmotor to directly turn the drawbar bolt. This eliminates the need for the bellevilles entirely (bellevilles add considerable complexity on a machine with a quill), and allows the drawbar to be loosened a little (if you're using Tormachs or other quick-change tooling), or a lot (if you're using R8) completely under software control. So, you can mix-and-match quick-change and non-quick-change tooling. The gearmotor I plan to use is only $140, and is capable of generating up to about 75 ft-lbs torque, which is MORE than enough to loosen even the most over-tightened drawbar. This is the simplest design I've yet come across from a mechanical standpoint. Tightening torque can be easily controlled with a current-limiting controller on the gearmotor. This can be as simple as a series-resistor on the motor when tightening.

Regards,
Ray L.

[The Blight]

I was told by a CNC service technician that this is how some of the big machines drawbar works.

Looking good!

[BobWarfield]

OK Ray, now you're closing in on having your cake and eating it too. I like that gearmotor idea.

Pretty good torque available from a cannibalized planetary drive cordless drill. They're compact too.

Looks like the drive electronics will be the catch, but you're just the guy to figure that one out.

Cheers,

BW

[HimyKabibble]

Originally Posted by BobWarfield OK Ray, now you're closing in on having your cake and eating it too. I like that gearmotor idea. Pretty good torque available from a cannibalized planetary drive cordless drill. They're compact too. Looks like the drive electronics will be the catch, but you're just the guy to figure that one out. Cheers, BW

Bob,

Actually, with a DC gearmotor, the electronics are trivial. The only downside, like with the linear actuators, is speed. I figure I can get down to about 4 seconds to grab or release a QC toolholder - not as quick as a belleville drawbar, but much simpler mechanically on a quilled machined, and far more flexible. Completely removing an R8 tool will, of course, be longer. Though there are ways around that as well - using the gearmotor only for final torquing and initial de-torquing, then a small stepper or DC motor to quickly spin the drawbar in or out once it's loose. My goal is still to be able to get up to a max. 25 ft-lb on tightening, which this should easily handle.

First, though, gotta finish my new quill drive....

Regards,
Ray L.

[pete from TN]

something like that system using the hydraulics and the actuator would be real nice if done like the tormach system is done with a kinda tower above the drawbar and the washer below the bellville stack being made into an easily removeable assembly and using the system you already have there would be real cool. If you can get the higher pressure tubing and maybe try to optimize the setup a little more you would really have something there. I sure like the idea of having the actuator remotely located and a very lightweight yet powerful drawbar atop the head like that. Again your toolchange speed is not earth shattering but to be honest with you for my purposes it really does not need to be. I can live with a four or five second operation time even with a toolchanger as these machines are just not that fast in the first place. The simple fact that I would have a toolchanger at all would make for a good time and improved production. Keep on keepin' on man... looking good....peace



Pete

[HimyKabibble]

BTW - If that's vinyl tubing you're using, replace it *real* soon. I use that for the air lines on my FogBuster and drawbar, and one day I accidentally hooked it up with the air regulator cranked all the way up. The tube exploded, making by FAR the loudest noise ever heard in my shop. It literally sounded like a gunshot and scared the crap out of me!

Regards,
Ray L.

[SScnc]

Pete, I have a couple of ideas to have the hydraulic cylinder able to swing out of the way quickly, such as, for example, the cylinder can have a horizontal sleeve or pipe on the left and right, the plates attached to the mill would have them also and a pin could be pulled out of one side and the cylinder assembly rotated to the upside down position giving complete access to the drawbar bolt. Then it can be rotated back into position, the pin slid back in, sorta just like gate hinges.

But I'm sure you have some ideas that will work better for your setup, just an idea I had. Yeah, I really like the fact that the "power pack" as I call it can be remote mounted and even out of site, like on the back or under the mill stand I plan to weld up soon with a much better enclosure than the crappy one I have now. I did switch back to the actuator mounted on the mill head like it was until I have time to refine the hydraulic setup a bit more. Hope you'll post pics of your prototype as soon as you have it.

Ray, The line I have now I think has a rubber hose inside as it's very soft when not under any pressure. It expands probably 50% when under pressure and I'm sure it would have already burst if not for the stainless steel braid on the outer of it. There's a scrap yard near me I was at recently and they had a bunch of actual hydraulic hoses that were cut off some equipment and are stainless steel braided, I think they were 1/4" ID which is perfect for this, I'll just have to find some connectors for the ends. I'm sure that was loud when that line burst, especially inside your shop. This summer I had my bicycle sitting outside in the sun and the back tire suddenly exploded and man that was loud ! Cheap Walmart tire on it, get what you pay for I guess.

Let me know if anyone has *any* ideas on improving this hydraulic setup.

Best,

Steve

[2_many_hobbies]

SScnc - Hey awesome work! Could you share some quick drawings on your cylinders?

Did you use any special o-rings for the pistons or just automotive parts quality ones?

[pete from TN]

Nice ideas man, to be honest with you I have been off work for four days now and been mostly in bed or on the couch with a cold or flu or something. I did manage to get out there today and finally install the encoder housings I machined on the X and Y axes. Just out of curiosity what is your ratio of the hydraulic cylinders? I know you said a 2" rod and 1" piston but what is the master and the slave sizes/ ratio? As far as the setup I would use for that as I said the way tormach did their system is very clever and would work a treat for your hydraulic over electronic setup. Mostly a tower with a clamping of the drawbar top to the bellville stack and underneath the large washer underneath them. It would seem that a well setup system that only really needs about .2" total travel would be able to actuate pretty quickly with your linear actuator somehow. Again nice work and good ideas. WHen I get over this cold I hope to get some time to play with this actuator myself... peace