X3 build - Kflop/Snapamp, Keling servos, AC servo spindle drive, cncfusion kit...

[oxford]

Thanks for the link

[yantra3d]

I spent a couple of hours blocking in this design for a power drawbar concept based on a pancake air cylinder mounted directly on top of the drawbar. My initial design was based on an air cylinder mounted inside the head but it didn't take into account the load applied to the spindle bearings. This design utilizes a floating plate that forces a ring up against the belevue washer stack whenever the air cylinder is activated. The plate is held in position by 4 spring loaded bolts fastened at each corner of the air cylinder's mounting plate. My hope is that It will relieve the pressure from the spindle bearings.

I am still in the early design phase and will likely go back to my initial plan to mount the air cylinder internally but I wanted to post this design to get some feedback from more experienced and knowledgable people than myself before I bother with trying to incorporate it into the final design. If anyone sees any flaws or has any advice to offer then please post it here.... I would greatly appreciate it!

[Quazar]

Very cool!

I was trying to puzzle out how to make use of the abandoned quill drive as a power draw bar. I was thinking I could attach a motor to the micro-feed, but I just couldn't figure out a way to do it that would be any simpler or cheaper than your approach.

Please post back as you make progress on the design and implementation of you power drawbar.

Cheers,
- Dean

[veteq]

Have to say you made some nice machines overthere!!!

Really nice write up.

Could you tell me how you are using the kflop?
Is it with the mach plugin or do you use software by dynomotion?

Kind regards.

Roy

[Quazar]

I've been thinking about this more, and I don't think I actually need a power drawbar since I don't plan to ever build an ATC for this machine. I just want something that allows for a quick change. Which got me wondering:

1. How much travel is needed for the Tormach Tool System to properly loosen/tighten?
2. How much upward force is needed to keep a TTS toolholder seated while cutting?

I was thinking I could just use a stack of belleville spring washers on the drawbar to keep it tight. Then I could use a cam or compound lever above the drawbar to press down and overcome the force of the spring and the friction fit of the toolholder. But, I really don't know what the design parameters are...

So, what stroke/force parameters were you using in your design?

Thanks,
- Dean

[SCzEngrgGroup]

I've been thinking about this more, and I don't think I actually need a power drawbar since I don't plan to ever build an ATC for this machine. I just want something that allows for a quick change. Which got me wondering:

1. How much travel is needed for the Tormach Tool System to properly loosen/tighten?
2. How much upward force is needed to keep a TTS toolholder seated while cutting?

I was thinking I could just use a stack of belleville spring washers on the drawbar to keep it tight. Then I could use a cam or compound lever above the drawbar to press down and overcome the force of the spring and the friction fit of the toolholder. But, I really don't know what the design parameters are...

So, what stroke/force parameters were you using in your design?

Thanks,
- Dean

"How much travel is needed for the Tormach Tool System to properly loosen/tighten?" - on the order of 0.100"

"How much upward force is needed to keep a TTS toolholder seated while cutting?" - That depends on how much spindle power you have, and what tools you use. For a small machine, like an X2, with a fractional HP motor, something on the order of 700-800# seems to be adequate. For a larger machine, with a 2-3 HP spindle, on the order of 4500# is required to adequately retain a 1/2" endmill taking a heavy cut. The Tormach power drawbar provides about 4500# of tension.

Personally, I think the best solution for a power drawbar to handle TTS (or ISO/CAT) holders at full capability (4500# tension), is a stepper motor, driving a high-ratio planetary gearbox. Using a NEMA23 stepper, this can easily provide 75 ft-lbs of torque to the drawbar, and give excellent control, so you can release just the TTS by giving the drawbar just a turn or two, or completely remove the collet by fully unscrewing it. The gearboxes are readily available for between $100-150. So, the cost is higher than the crude impact wrench solution, but far more versatile, quiet, and no Bellevilles and custom drawbar bolt required.

Regards,
Ray L.

[Quazar]

Thanks for the numbers - that really helps!

... so you can release just the TTS by giving the drawbar just a turn or two, or completely remove the collet by fully unscrewing it. ...

But doesn't the drawbar require some downward force for the toolholder to release? Using a standard R8 collet requires a few taps with a deadblow hammer to overcome the collet's friction fit. Are the TTS or other quick-change toolholders machined to somehow release just from lack upward pressure?

Thanks,
- Dean

[SCzEngrgGroup]

Thanks for the numbers - that really helps!



But doesn't the drawbar require some downward force for the toolholder to release? Using a standard R8 collet requires a few taps with a deadblow hammer to overcome the collet's friction fit. Are the TTS or other quick-change toolholders machined to somehow release just from lack upward pressure?

Thanks,
- Dean

Yes, some downward pressure is required, but not a great deal. That can easily be provided by a pneumatic cylinder. When I built my power drawbars, I found it required no more than a few hundreds pounds of static down-force to release the taper, so no elaborate mechanism is required.

Regards,
Ray L.

[yantra3d]

Thanks a ton for all the great info Ray... much appreciated! I think your idea of using a stepper motor and gearhead is a great idea... I am definitely going to give that some serious thought before I move ahead with the air cylinder. The concept sounds ideal. What size gearhead would you recommend? I have a 5.5:1 and some 3:1's that are really nice (got a steal on them). Thanks for the tip.

Hey Dean, I will be activating the drawbar through gcode for a simple ATC rack at some point in the future but for now I plan to use this pedal (see pic). I already have the electronics set up to control the Fogbuster and Drawbar solenoids so I will definitely make use of them. (unless I decide to go with a stepper/gearhead instead!)

I really like your idea of making a manual drawbar lever though... great idea! BTW, I'm actually using a small stack of bellevue washers right now which I really like cause it keeps me from cranking down the drawbar too tight. (I have a bad habit of over-tightening it!) Just two of them stacked like this () works great.

Hey Veteq... you are the first person to ask about the Kflop!! Right now I am using it with just the KmotionCNC software and am content with that for the time being. I plan to move over to the Mach3 (already have a copy) via the plug-in once I get everything dialed in with the Dynomotion software. Right now I am trying to get the rigid tapping setup and then I should be set to switch over to mach. KmotionCNC is not too bad to work with and I am using a Logitech joystick and also touchscreen with it so it's keeping me satisfied.

Man, I just started using some Accupro endmills and I am just loving it! I started with those cheap asian ones (set of 2 and 4 flutes) and the difference is unbelievable! As bad as the cheap ones are I would still highly recommend someone starting out to get a set to begin with. I have broken about 5 of them already. If/when I break one of these accupro's I'll be in tears! lol

[oxford]

Are you programing strictly in G-code or do you use C with the kflop?

How easy is it to set up?

Are you switching to Mach 3 because of the user interface?

Thanks

[veteq]

cool its working ok, let us know how the plugin goes and if it works allright.

[yantra3d]

Hey Oxford, I picked up my copy of Mach about a year before I got the kflop so my original plan was always to use mach3 but I am satisfied enough that I haven't rushed to move over. I originally started out with the Grex G100 and g320's but that quickly turned into a dead-end road. I was waiting around for the smooth stepper at the time that I was looking to get out from the grex but when the spindle syncing didn't progress as quickly as I hoped I decided to go with the kflop cause Tom at dynomtion offered to work with me on the spindle syncing. It seemed to be the most promising of the bunch. We started on my lathe with threading and now were working on rigid tapping for the x3 mill.

As far as being user-friendly goes; it's pretty straightforward and so it's simple and easy to work with. It doesn't have near the features that mach does but it runs really solid. I wish Tom would let me re-design the interface to be more touchscreen friendly or it would be nice if it were more customizable but it gets the job done so I can't complain.

To set it up you have to compile the c codes but that's really easy once you get going. Basically you have the motor tuning setup screen and once you are happy you just copy the config to the clipboard and paste it into the c program compiler for an uber code that drives everything. The digital I/O bits for enabling or home and limit switches are easy to set up since Tom has pretty much created all the coded scripts that can be used as templates so all you need do is sub out your particular bit or input #'s in place of the existing ones. Creating buttons in kmotionCNC (like spindle enable or homing) based on the scripts is really easy and the same goes for the S and M commands... You just add the path to the script using a drop-down menu and they're ready to go.

When I started using it I was completely clueless (this was/is all new to me) but Tom is very helpful and so it didn't take long to get up to speed. Looking back now I would say that it's not difficult at all and for someone with a little experience or who is tech-minded would find it a breeze to figure out.

Overall I am very satisfied with it and can say that it's been the least problem of the whole build. Very good quality product and well worth the investment IMHO. I don't regret going this route at all and I wouldn't hesitate to recommend it. Frankly I'm surprised that more people haven't picked it up.