Current ballpark cost build vs buy~
My background is being a toolmaker that programmed and used various CNC Bridgeports and Hitachi Seiki VG45 mills and lathes.
I have the urge to buy or build a benchtop CNC mill for small parts , engraving and I miss G code programming.
Just starting to read the many forum posts and curious what's a well equipped and built table top machine cost Vs buying a decent one ?
I love the table top Tormach but man , its priced like a lot bigger machine.
Buying an XY table , ball screws and motors adds up fast.
My ballpark working volume would be X / 10" travel , Y / 6" and open on Z.
Opinions please~
Jeff in Ohio
Re: Current ballpark cost build vs buy~
A G0704 or PM25 would do that volume.
You are going to spend like $2000 plus the cost of the mill for a basic conversion. I'm sure you can do it for less, but realistically if it is done right I think $2k is about right. It will be a grand for the ballscrew conversion kit plus the cost of the control and various other bits. If you want to get a bit more thorough, for example some sort of enclosure, coolant, spindle motor, power drawbar, etc., you will spend more.
Re: Current ballpark cost build vs buy~
Enclosed machines are great for production and using coolant.
It also works against you when you have a long part than does not fit inside the enclosure.
I have several Bren guns I am restoring and want the capability to engrave them correctly without having electro etch stencils made and using.
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Re: Current ballpark cost build vs buy~
The Intelitek BenchMill 6000 / Tormach 440 is close to what I would like to have or build~
Re: Current ballpark cost build vs buy~
Jeff,
This may not be a reasonable comparison as I sort of went nuts on my project, but when it was all said and done, it was 11K.
A person could probably purchase a small commercially available machine for less than this, but as many here know, this was a father and son project, so cost wasn't am important as spending time in the shop with my son.
With end doors on the enclosure like on the 'Grizz', machining long items is not an issue.
Stuart
Re: Current ballpark cost build vs buy~
Take a look at the Taig mills. I doubt you could build one for what they sell for, especially if you didn't have a well-equipped machine shop to start with. They recently introduced an expanded Y axis option, which gives it more than 6 inches of usable travel (see https://computersculpture.com/taig-m...-cnc-equipped/ but ignore the part about the spacer - the newest iteration does away with it in favor of extended prismatic steel bars.) The X travel is already about 12" (a little less on the ball screw version, to make room for the nut). Another new improvement is the variable speed 3/4 hp motor option, which also has wider belts and a double pulley arrangement for enhanced torque. Its 11,000 rpms (vs 10,000 with the standard motor) gets you into engraving territory, although it's easy enough to mount a higher speed tool if needed.
Re: Current ballpark cost build vs buy~
After using real / full size machines I know a smaller machine will have more limitations.
I am mainly focused on accuracy.
Small engraving with arcs and radius it only take a little table movement error , or lack of moving to make it look like crap.
Some very good suggestions and I will be doing some reading in depth.
No getting around good ball screws and servo motors like NEMA 34'ish in size.
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After using real / full size machines I know a smaller machine will have more limitations.
I am mainly focused on accuracy.
Small engraving with arcs and radius it only take a little table movement error , or lack of moving to make it look like crap.
Some very good suggestions and I will be doing some reading in depth.
No getting around good ball screws and servo motors like NEMA 34'ish in size.
Re: Current ballpark cost build vs buy~
I too would go larger than the 25 size mill if I could. I bought what I could fit down my basement stairs at the time, and it is still working, though in a much larger shop at this point. I machined for 5 hours today with my 0704. Everything came out pretty nice.
That said, in steel it is marginal. I make it work, but it is touch and go. I occasionally bore some hardened steel bearings with it, and I struggle to get +/-.003" with that, frustrating indeed. In aluminum I can do 1/3 that. In soft steels I can do better, but the machine really struggles with any hardened steel. For that specific part, it's part poor fixturing and part machine limitation. It is hard to hold an assembled bearing and bore the inner race, I guess I can give myself that.
For engraving you will definitely want a high speed spindle, but machine rigidity won't be as much of a concern. "Accuracy" as far as engraving is concerned means very little. It's a very easy target to achieve even with a very modest machine.
My machine uses nema 23 on XY, they work perfectly fine. For a larger machine 32s might be needed, but if well setup probably not. Finding some used clearpath servos and running them 2:1 is probably your best bet for long term performance. I am working on that now with my machine, I have all the servos but haven't had the time to machine the new brackets to adapt the servos and belt drives. That said, I have machined for thousands of hours with steppers. It can be done and will be very reliable with good machine adjustment. Building a machine and tuning it yourself can take years though. I have made many parts, but I have also ruined many parts as a result of bad machine adjustment. After like 7 years the thing is pretty well dialed in. I machined 20 perfect slip fit pockets for spherical bearings yesterday. They came out perfectly to size as modeled. Aluminum is easy to work with though.
Re: Current ballpark cost build vs buy~
The more I look the more I really think I will be building something.
I need to start and Excel sheet and add up a decent XY table , ball screws , drive and motors, etc.
Nothing close to my area for used equipment.
Re: Current ballpark cost build vs buy~
I converted my G0704 with clearpath servos... 3 servos, cables and power supply: A bit more than $1500... I'm really happy with them, good luck!
