My Build - I blame you lot for this....!

[Lee Roberts]

Geeet your beavers outtttt, Geeet your beavers outtttt, Geeet your beavers out for the lad !

[HiltonSteve]

Been playing with my machine for a few weeks now and everything is running sweet, the only problem I have is getting rid of the dust / chips when cutting wood and MDF, its amazing how much crap a 6mm cutter can create in very short space of time! Up to now I have been using our old Dyson vacuum which to be fair does a reasonable job but not really up to continous use and will soon be dead if I carry on abusing it!

So yesterday I went out and bought myself a small(ish) dust and chip extractor (see photo's below) which came with a standard 4" flexible pipe, this baby is quieter, shifts a lot more air and is built to run continously.

Now I have seen the router dust extractor mounts that fit around the spindle with the brush's and plastic flaps but just did not like the idea. Seems to me that they will probably end up getting in the way when cutting or changing tools so.... I had an idea and knocked up and bit of a prototype out of a couple of bits of MDF and the top off of an old 4" drain pipe connector this afternoon (see pics).

First test run it worked very well, cut a few deep slots in some MDF and when finished there was little or no dust or chippings around at all.

Still a bit bulky but just wanted to prove the theory a this stage, final design will probably incorporate the router mount into it and make it all out of aluminium.

But before I go any further with this has anyone seen or used anything similar that may be able to throw a few other ideas into the pot???

[ptjw7uk]

Most of the professional ones have a brush curtain to contain the 'splash' from the cutter. Only problem I foresee is that if the base gets to large then it will restrict the x and y movement. It would be great if the system could actually surround the router could aid cooling but would be very hard to design.

Peter

[HiltonSteve]

I have been doing some feed/speed calculations for cutting wood and mdf and found that my feedrates are nowhere near what they need to be to give me the correct chipload, this would explain why my carbide cutters seem to produce a lot of dust in mdf and dull off quite quickly.


Calculation -

Chipload required for MDF with a 6mm cutter = 0.33-0.41
My min spindle speed with Kress 1050 - 10,000rpm
No of flutes on cutter - 3

Feedrate = number of flutes x chipload x rpm

So... feedrate = 3 x 0.33 x 10,000

Feedrate = 9,900 mm/min !!!!

A 2 flute cutter would drop this to 6,600 mm/min, but this is still pretty high.


The problem is my machine only had a max feedrate of 2900mm/min, played with all sorts of settings when i first got it running but that was the best I could get. Feedrates/rapid speeds above that and I got stepper motors stalling and missing steps, but tonight i decided to have another go. So, I switched everything on and found for the first 2-3 mins I could get my feedrates up to 7,000 mm /min but then I started getting stepper problems, kept bringing the values down until the problems went away and guess what the feedrate ended up at.... 2900mm/min!

Took the top off my controller box to see how hot the driver cards were and found that the heatsinks on them were seriously hot, you could only hold your finger on them for 5-10secs. So I decided to do a bit of a cooling mod....

Found a couple of 120mm 12v PC fans and made some mounts for them, fixed them over the top of the driver cards which more or less covered the cards completely and wired them up to a spare 12v supply. (see photo's below)

I now have the motors running at 5,000mm/min without any issues and the driver cards don't even get warm. I did wind it up to 7,500mm/min but to be honest I think its just too fast for the machine, 5,000 looks and feels much more comfortable. The next problem was acceleration and decel, had to wind this up to 1000 mm/sec to get square corners when cutting rectangular pockets. I may have to screw the machine down to the bench now to stop it from throwing itself off!

Now running at these speeds it looks feels much more aggressive, maybe a bit too aggressive but does seem to cut a lot cleaner and a damn site quicker.

Conclusion - Cutting MDF can be a bastard nightmare, it can give you cancer and knackers your cutting tools. Looks like I might steer away from using it too much in the future. But from what I have read most woods are in a similar chipload window so still need similar feedrates to the above, may look at getting some 1 flute cutters so I can reduce the feedrates and see if they are any better.

Anyone else finding the need to run this fast when cutting mdf/wood?

[John S]

Single flutes are the way to go, It's not so much chip load but space to get the chips out the way so you are not recutting chips.

Couple of people on Ebay selling Trend single flute router cutters in carbide.

I use these on Tufnol which is very abrasive and they last a long time.


Never tried Roy's 5 amp drivers as I have a load of the 7.8 amp Chinese drivers. Was running bastard Gecko 201's but these Chinese drives outperform them easily, better rapids, cooler running but best off all they don't blow up on switch on now that Marriss has now kindly admitted to on the zone.

[HiltonSteve]

Never tried Roy's 5 amp drivers as I have a load of the 7.8 amp Chinese drivers. Was running bastard Gecko 201's but these Chinese drives outperform them easily, better rapids, cooler running but best off all they don't blow up on switch on now that Marriss has now kindly admitted to on the zone.

Don't get me wrong, I am not saying that there is anything wrong with Roy's 5A drivers, just that if anyone is thinking of using them then make sure you keep them cool, maybe what I have done with the cooling is a bit over the top with the 2 x 120mm fans, I was only looking for one fan and found two so I thought I may as well stick them both in whilst I am at it.

But now they are cooler they run just fine.

I will have a hunt round on ebay and get myself some of those single flute cutters, they do sound like the way to go. Ta.!