CNC Questions

conetip

conetip

AzB Silver Member
Silver Member
If you were to do it again with cnc, lathe or router/mill,
what would you do differently?

I am looking into making a cnc flatbed machine.

I am researching the options, and after peoples opinions on what they would do differently on round 2

I have sorted out a couple of motor/ spindle options.
Thinking of going with Mach3 ,
Not sure of, the stepper versus servo motor,
rotating ballscrews, or rotating ball nuts

Controllers ?

Any help will be appreciated.
This is a long term project with a 2 year time frame.

Neil
 
I have gone several rounds.

Mach 3 is a good choice. I would just stick with stepper motors unless you have ever worked with servos. The bang for the buck is not there. I would use a Gecko 540 system. Oh and I am a fan of the Smooth Stepper. I would choose anti backlash lead screws over ball screws as the saw dust will not effect them as bad.

Before you start, ask yourself what are you going to do with this machine. Is it for tapers or inlays. You may want it to do both however, I have found that a dedicated machine is the way to go. For inlays, there is only one way to fly. That is with a spindle that has an ATC on it. If you have ever seen one of these you will know what I mean. I have broken more bits putting the bit in and out of a spindle than actually cutting inlays.

One last thin, home switches, home switches, and home switches. I can tell you how much I love them on my machines.

good luck, Jim.
 
Last edited:
Mc2 said:
Mach 3 is a good choice. I would just stick with stepper motors unless you have ever worked with servos. The bang for the buck is not there. I would use a Gecko 540 system. Oh and I am a fan of the Smooth Stepper. I would choose anti backlash lead screws over ball screws as the saw dust will not effect them as bad.

Before you start, ask yourself what are you going to do with this machine. Is it for tapers or inlays. You may want it to do both however, I have found that a dedicated machine is the way to go. For inlays, there is only one way to fly. That is with a spindle that has an ATC on it. If you have ever seen one of these you will know what I mean. I have broken more bits putting the bit in and out of a spindle than actually cutting inlays.

One last thin, home switches, home switches, and home switches. I can tell you how much I love them on my machines.

good luck, Jim.
Click to expand...

The only ATC I am familiar with is those on milling machines, either the carrousel or magazine type with an arm that rotates taking a tool from the spindle and pot then rotates.
But they require a special spindle. Have you a link to a more simple type that can be fitted to a router?
If the ball screws had the seals and positive lube, why do they have problems? Just trying to understand, as the industrial machines I am familiar with all use Ball screws with positive lube on the nut.
I have not brought anything yet, still in the design and layout work type stage. I do all tapering on my special lathe,this is for milling and maybe inlays, points, cowls for model planes, all wood work.

Thankyou for those that have responded and sent mw pm's with info.
Thanks, Neil
 
Mc2 said:
http://www.ebay.com/itm/Precise-Spi...ultDomain_0&hash=item20bc979d9b#ht_860wt_1392

By hitting the top of the spindle with 85 or so psi, the tool is release out of the collet. It clamps back up when the air is released.

As far as the ball screw goes, I suppose that positive pressure would keep the dust out.

Jim.
Click to expand...

Nice spindle. You'd think he would put more info on something he's trying to sell for $3,300. I found this Data sheet that gives the specs. Looks like the runout is 80 millionths, liquid cooled, air clamp release. Looks nice, not sure about $3300 nice but I like it.

http://www.fischerprecise.com/uploads/media/ESC-3043.pdf

I see it says ATC but I think this only means it will release the tool via air. I am curious about is how it works though. It says collets so either it uses a Retaining Nut or a Drawbar. I'm guessing the former and with collets you'll lose you tool length each time. If it had something similar to the R8 or Cat40 toolholders than I said you could make a full fledged ATC. If I am wrong about any of this I'd be interested in hearing the particulars
 
bruppert said:
Nice spindle. You'd think he would put more info on something he's trying to sell for $3,300. I found this Data sheet that gives the specs. Looks like the runout is 80 millionths, liquid cooled, air clamp release. Looks nice, not sure about $3300 nice but I like it.

http://www.fischerprecise.com/uploads/media/ESC-3043.pdf

I see it says ATC but I think this only means it will release the tool via air. I am curious about is how it works though. It says collets so either it uses a Retaining Nut or a Drawbar. I'm guessing the former and with collets you'll lose you tool length each time. If it had something similar to the R8 or Cat40 toolholders than I said you could make a full fledged ATC. If I am wrong about any of this I'd be interested in hearing the particulars
Click to expand...

Bruppert

I have one of those spindles and let me tell you, they are the nuts!

Yes, the ATC is basically just an air actuated tool release, but that by itself is extremely useful. It does use a draw bar type collet system, and it does "pull back" a little. But that doesn't mean you couldn't build a tool holder system and have it do fully automated tool changes. It's something I have planned in the future for sure. The main advantage the big machines have with the BT or CAT style tool holders is that they provide a way to maintain tool length. With the depth rings on the small bits we use, you can get the same thing.

Neil, as for the positive pressure lubricated ball screws, yes they would work, and work pretty well. The issue I have is basically you are spending allot of money that you really don't need to. First, typical inexpensive ball screws are not low or zero backlash. The only way to really get very low backlash with ball screws is with expensive ground screws, or double offset ball nuts. They work great, but they are expensive. On the other hand, you can get high quality lead screws and use simple but effective anti-backlash nuts and have the same performance. They really don't need any lubrication so you don't have any of that expense or difficulty.

Just my thought!

Royce Bunnell
www.obcues.com
 
I am now seeing why people just make a basic setup and use the backlash nuts.
Looking at other threads, there is a learning curve on setting up Mach3 as well.
Thanks all for the input.
It really does look like you definitely only get what you pay for.
Neil
 
conetip said:
I am now seeing why people just make a basic setup and use the backlash nuts.
Looking at other threads, there is a learning curve on setting up Mach3 as well.
Thanks all for the input.
It really does look like you definitely only get what you pay for.
Neil
Click to expand...

In some ways, it's more of a learning hill than a learning curve!!!

I just changed out my controller to a Gecko G540, so am starting over from scratch with regard to motor tuning.

Practice makes perfect they say! :smile:

Gary
 
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