CNC Router HELP

[herbs0962]

Be gentle absolute beginner here!
I currently supply metalwork to a customer, who is now asking for me to supply a MDF frame as part of the kit.
The frames are made up of 4 sections from 22mm board 65mm wide , screwed and glued together, there are various hole sizes and cutouts on one face and a large rebate (12x40mm) running the length of the strip, the strips vary in length from 250mm to 1800mm
We currently us CNC punching machines, so I am keen to stick with this principle.
I am looking for advise on :
1. Can I take a 8x4 sheet machine the holes & rebates then profile the outer shape, this is what we do with steel, using micro tabs to hold the component, then shake it out, but with MDF will this just tear?
2. What machines/makes are recommended, this is will be a production machine so am looking at it for the long term, to take 8x4 sheet tool change facility (6 tool holders) happy to look at used machinery, which I guess I would have to with a budget of £10~£15k

Thanks

 

[sploo]

If I understand what you're asking, this should be pretty trivial for a CNC machine. Even most hobbyist type machines will happily cut shapes, pockets and rebates/dados into MDF. The main cost issues are size (of machine) and cutting speed.

I've been running a K2 CNC KG3925LT for years, with a Porter Cable 892 router as a cutting head. It'll happily do 1/4" deep cuts in MDF with a 1/4" carbide spiral upcut bit at 120ipm (approx. 50mm per second). I tend to be quite conservative with speeds, but I've seen one of their machines do deeper cuts with a 1/2" bit and a proper spindle.

Depending on what I cut, I tend to either onion skin (leave a thin layer all the way round a part), or leave small tabs (approx. 3mm thick, 10mm long). In both cases I cut the parts off the sheet using a Stanley knife, then clean the edges/tabs with a trimming bit on a router table.

If you tried to pull the pieces out then yes it’d probably tear. However it you shaped the tabs such that they had a very thin point in the middle then you might be able to get the tearing to happen on the tab, but you'd still need to do a clean up with a trimming bit. With a tool changer you might be able to select a thin bit and slowly cut through most of the tabs at the end of the job, in order to minimise manual clean up work.

If you wanted to go for no tabs/onion skinning then you might need to look into vacuum hold down - though some people use double sided tape with success.

In terms of brands, my K2 machine is popular with guitar makers, though I only put hobbyist load levels on it. They do make 8x4' machines, but I'm not familiar with them.

From frequenting CNC specific forums such as CNC Zone, it seems the Shopbot 8x4' machines are popular. Both K2 and Shopbot look to have machines in this size range in the $15k USD region, and I found it wasn't too bad importing from the US (at the time the shipping + ~4% duty + VAT still resulted in a better/cheaper machine than anything I could find in Europe).

Hope that helps.

 

[RobinBHM]

A budget of £15k would get you a 2nd hand industrial cnc router designed for the woodworking industry. At there moment there is a masterwood winner 2.45 for sale at scott and sargeant. It is a good make with a uk agent.

You can certainly get a lot for your money on a used machine, but beware some of these machines may have been running a double shift 5 days a week. You will need technical support and spares back up make sure the brand is well supported in the uk. Most of the machines seem to be italian. In addition to the puchase there will delivery, installation, extraction, commissioning and training all of which could cost a fair amount

Other makes would be Biesse, SCM, Morbidelli -all italian.