My name is Malcolm Reade and I own a (very) small plastics injection moulding Company based near Northwich in Cheshire. Ours is probably one of the oldest surviving model manufacturing companies in the UK having been founded in 1945 at the end of WW2.
We manufacture small precision components (up to 3/4 ounce) for the wholesale, retail and kit manufacturing model trades world-wide using bench-top hand/pneumatic operated injection moulding machines.
I'm looking to improve our mould making processes by using CNC routing techniques - we make our moulds from flat brass bar stock.
Brass is the material of choice, it's easier to machine than steel and requires no coolant - which tends to obscure visibility when making precision cuts at close quarters. We also find that (contrary to expectations) that brass is extremely durable with very little wear in use.
Some of our moulds have been in constant (almost daily) use since the early 1950's and were made by my late father mostly on a Myford ML7 lathe equipped with a vertical milling slide.
We have moved on from that era to some extent in that we now have a small milling machine, hydraulic press etc. to complement the original equipment.
I have been reluctant to buy an "off the Shelf" CNC Router - most are Chinese Imports and probably have very little, if any, available UK based technical support, and I have been absolutely horrified by the prices charged by UK based manufacturers.
I guess the best option would be for me to build one? I am a professionally registered engineer with nearly 50 years experience, (mechanical, control engineering, instrumentation etc.) so this sort of project shouldn't be beyond by abilities.
We only need a very small bench-top CNC router, our maximum component size is probably only 2 inches high x 3 inches long x (say) 3/4 inch deep. Smaller components are often manufactured in multiples in the same mould though.
Our maximum mould size is 3 inches high x 4 inches wide x 2 inches deep.
Could any of you kind folks point me in the right direction please?
Hi Malcolm, I'd be looking at a small milling machine and converting that to CNC as your work envelope is so small...that is if you're going to use it just for work and not the 1,000,000 other things you'll think of to make with a CNC router!
Last edited by njhussey; 29-06-2014 at 04:52 PM.
Thanks for your reply.
As luck would have it, I have a brand new and unused Axminster Micro-Mill sitting in my workshop that I think might be an ideal candidate for conversion to CNC - providing that I could get information on suitable stepper motors, controllers and all of the other bits necessary to make the conversion?
The micro-mill probably (certainly) isn't the best performer in the milling machine market, but it would be perfectly adequate for my needs - providing things like backlash issues etc. could be suitably resolved. It would also have the added benefit that it IS a milling machine, not just a glorified engraver.
I wonder if anybody on the Forum has done a similar conversion? I would be glad to hear from them if they have.
I have seen upgrades on the internet for improving the Micro-mill's drive train - the plastic gearwheels that come with the machine as standard are pretty basic and liable to fail although I have taken the precaution of having spares in stock.
Sounds like the right scale of thing to do on something like a second-hand Denford CNC mill? They do appear on the market from time to time. New, there are machines from Amadeal, ArcEuroTrade, Axminster, etc, if buying new fits your business model better. But a build log if you roll your own would be interesting to see!
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To be honest I wouldn't go with converting a mini mill for this work. End of the day they are toys and over priced toys at that. You would basicly end up scraping half the machine just to get it to perform any thing like acceptable. Even then you will still be left with sloppy dove tail ways needing constant adjustment to keep accurate.
With your knowing exactly the purpose of the machine and your small work requirements then you could build a far stronger and more accurate machine custom to your needs that use's quality profiled linear rails, ballscrews and all the trimmings for less money than buying and converting minimill.
if building id also consider going for a fixed gantry type ,Ideal for the sizes your working with,easy to knock up and will only require one ballscrew and stepper motor on the X axis.
If Building, I am sure that a fixed gantry machine would be best for you, but I personally think that you would be better to go down the milling machine route, not a manual machine converted, but a purpose made CNC mill. Something like a Boxford or a Denford machine. There are quite a few that have already been changed to run with Mac3, but I understand that the later machines used a usb interface and had good CASD/CAM software. G.
I know a guy with a Denford nova mill on a stand with plastic roll over cover including the software (probably needs converting to Mach3) I am sure it has ball screws all round. It looks very clean. If anybody is interested I will pm his number. ..Clive