A slightly larger 'Benchtop' machine...

Posted 8 years, 7 months ago    11 comments

While we await information on parts availability for the first machine (to allow us to offer the best 'bang for the buck') here's a peek at a larger machine for the builder who needs more capacity. With full way covers for flood coolant, servo axis drives, and oversized THK linear bearings, this is another solid, durable machine.

This is stretching the definition a bit - travels on this machine are 30" x 16" x 16" XYZ (750 x 400 x 400 mm). As for it's smaller sibling, this is intended to be suited for high precision work using light cuts at higher feed rates, not heavy cutting.

Fast rapids are more important as the travels increase, and the larger X travel means a larger ball screw is desirable to avoid potential vibration or whipping at higher speed. This design calls for 25 mm dia., 5-8 mm pitch ball screws. These screws will give us slightly more force for a given motor torque than the 10 mm pitch planned for the smaller machine, enabling us to use the 70 mm frame brushless servos on this machine also. We will be using some ground NSK 25 x 8 mm pitch screws for our build, and we expect peak feeds in excess of 600 IPM or 15 m/min.

The spindle will again be interchangeable, this time we'll be building our own 2.5 Hp ER32 collet direct drive spindle which will be complemented by a 1.2 Kw, 50,000 rpm KaVo HF (high frequency) spindle.

 

Update: 

We've now started building this machine, and our version will be a steel one, rather than aluminium - after much consideration, it was decided that steel would be a better choice for a machine this size.

We've chosen a grade of steel we hope will behave well and remain stable without warping or twisting unduly, and will hopefully machine nicely also. The cost is similar by volume to Aluminium, but it should be much more rigid. The article covering the build is Here


Comments

Jason
8 years, 7 months ago
Hi, Im in the UK and very interested in your larger mill, can you estimate when plans / parts will be made available.
8 years, 7 months ago
Hi there,

Actually, I had this one scheduled to build after the smaller mill, but if there's more interest in the bigger one, I could do it first.

The plans are mostly done and the electronics, servos and drives are all available now at www.zealcnc.com. I do also have limited quantities of the more awkward to locate parts including ball screw mounts & way covers, though I haven't listed them yet.

Feel free to drop me a line if you'd like any more specific information - there's a contact page on the www.zealcnc.com site

Regards,

Jason
Dan
8 years, 6 months ago
Would this mil be suitable for milling aluminum?
Would I be able to fit a 4th axis to it at a later date?

Regards
Dan
8 years, 6 months ago
Hi Dan - yes, to both questions. It won't be suitable for a heavy cut, but for lighter cuts it will handle harder materials just fine. Either a head or table mounted rotary axis could be added without undue difficulty also.

Regards,

Jason
Dan
8 years, 6 months ago
I’m sorry for the question; I’m still new to CNC and machining,
What is meant by a heavy cut and a lighter cut for harder materials?
8 years, 6 months ago
I'm Just referring to a cutting path that only removes a small amount of material per pass, as opposed to a heavy cut that removes more material each pass. Maybe take a look at these two videos, hopefully they will help show the difference.

This would be a light cut: http://www.youtube.com/watch?v=mcUqS9t0Yyw - This is a good way of reducing the cutting forces, so you can use a lighter machine like the one illustrated above.

An example of a heavy cut: http://www.youtube.com/watch?v=uAcBU2iqkKE -A heavy cut like that needs a very big, rigid machine which is not very practical for the average person to build.

Hope that helps,

Jason
Aristo
8 years, 6 months ago
Hello,
I also interested in your big mill. Does this mill use linear bearing and ballscrew on all axis? Can we use bigger motor to do heavy cut? Thanks. Aristo.
8 years, 6 months ago
Hi Aristo,

Yes, this mill uses ball screws and linear bearings on all axis. It wouldn't be as suited to heavy cuts as a good knee mill, which is why I'm converting my Chevalier mill to CNC for my own needs. This one could probably handle up to 3/8" cutters, with an appropriate spindle. The capacity could be increased by making the frame from steel instead of aluminium plate.

Regards,

Jason
Dan
8 years, 4 months ago
What sort of ball park figure would it cost to put this togeather?

Can a 4th axis be added?
8 years, 4 months ago
Hi Dan,
Cost for this build would be in the region of US$7,500 / NZ$13,000 depending on spec - using ground ball screws and a good spindle would push it up, if you used one of the chinese spindles and precision rolled screws, you could probably do it for less. No problem to add a 4th axis, we are looking at the possibility of a 5th axis also.
Regards,
Jason
Dan
8 years, 4 months ago
5 axis mill will be just what im looking for, im looking forward to seeing the next part of the build

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