Author Topic: Proxxon MF70  (Read 5360 times)

Offline Roger B

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Proxxon MF70
« on: December 17, 2017, 12:31:16 PM »
I decided that I would find a small (very small) mill useful in addition to my Hobbymat combined lathe and mill. The Proxxon MF70 fitted the space requirements but reading up on it there were some potential problems:

1) The collet chuck would accept a maximum size of 3.2mm
This limited the choice of cutters. It obviously is not suitable for large diameter mills, but it also means that the normal 6mm shank small mills cannot be used. There is a commercial ER11 conversion available but at a price.

2) The speed range was high, 6000-20,000rpm and the torque was low with a 100W motor.
Again this potentially limits the cutter size but the machine is simply too small for bigger cutters. There is a commercial 4-1 epicyclic conversion available giving 1500-5000 rpm but this again is not cheap and will restrict the use of very small cutters.

I received the machine and gave it a couple of trials:

The first was cutting a 2mm keyway in a 4mm dia stainless steel shaft. I fitted the Proxxon supplied 2mm end mill and set the speed to 10,000rpm. The initial cut at a depth of 0.2mm was fine. I then increased the depth to 0.4mm This worked but sounded a bit laboured. 0.3mm was also ok. The keyway was straight and a close fit on a piece of 2mm key steel.

The second trial was to mill a 2mm square key from a piece of 3mm diameter stainless steel rod. I used the 3mm end mill for this still running at 10,000rpm. The first cut was 0.1mm depth and the next two were 0.2 mm depth without problems.

Maybe the issues are not so big and running with 'Proxxon' style cutters it will be fine  :)

Out of interest I took it apart to see how easy it would be to make an ER11 chuck fit and make a lower reduction, 2 or 3 -1, gearbox.

The spindle is 10mm diameter with a double keyway. An ER11 collet chuck with a 10mm shank is easy to find (16EUR from CTC for example). The recess bellow the motor is 32mm diameter so I would need to find a suitable ring gear to fit.
Best regards

Roger

Offline Bluechip

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Re: Proxxon MF70
« Reply #1 on: December 17, 2017, 12:51:01 PM »
Roger

Pic. #5 
Are the mains input cables pressing up to the component tails on the PCB ?

If so, you need to rectify the situation before the cable insulation gets pierced and     :zap:    :'(

I'd remove the PCB and snip off the long bits, then get some thin insulation sheet and slide it down the gap.

Dave

 

Offline Admiral_dk

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Re: Proxxon MF70
« Reply #2 on: December 17, 2017, 04:57:28 PM »
Congratulations on a new Toy Tool  ;)

I hope that you get much joy from using it  :whoohoo:

Online Kim

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Re: Proxxon MF70
« Reply #3 on: December 17, 2017, 06:15:22 PM »
Nice little machine, Roger!
New toys are always fun! :)
Kim

Offline Roger B

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Re: Proxxon MF70
« Reply #4 on: December 18, 2017, 08:48:52 PM »
Thank you all for the comments  :ThumbsUp:

Dave, I thought it all looked ok but after your observation I took the cover off again. There is ample clearance between the mains cable and the PCB. I think that in the picture 005 I had tilted it when I was looking inside. There is a support V sort of thing in the cover to keep it in the correct place.
Best regards

Roger

Offline Roger B

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Re: Proxxon MF70
« Reply #5 on: December 23, 2017, 11:03:02 AM »
The next trial was milling a couple of flats on a length of 4mm brass rod (to make a replacement tang for a belt buckle). This was with a 3mm end mill at the recommended 20 000 rpm, depth of cut 0.8mm. This cut as fast as I could turn the handle but brass swarf all over the place  ::)
Best regards

Roger

Offline Roger B

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Re: Proxxon MF70
« Reply #6 on: December 27, 2017, 07:14:22 AM »
The Z axis feed was not as smooth as I would have liked and the scale ring seemed to be rubbing on the top cover of the column. I took the top cover off and wound the screw out of the head. The screw is fixed/adjusted by an M6 left hand nyloc nut. I took this off and there was negative clearance between the end of the handle that should have been the thrust face and the thrust face on the top cover. This was quickly sorted with an M6 washer. I also added a hard shim washer on both sides of the plastic top cover. I don't know why this problem existed, there didn't seem to be anything missing according to the parts list  :headscratch:

I then tried it's capabilities a little more. I needed to make a guide bush for a broach which required a 3.3mm wide 5.5mm deep slot. I could have set up the Hobbymat but though I would try it on the MF70. With a 3mm mill at around 7000rpm I cut the slot in 0.5mm steps and then widened it 0.15mm either side. It only sounded a bit laboured when passing through the flange otherwise ok.
Best regards

Roger

Offline Roger B

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Re: Proxxon MF70
« Reply #7 on: January 07, 2018, 08:36:41 AM »
The next test was with the 1mm dia. cutter. I needed to mill a 1.4mm wide 1mm deep slot in a piece of 5mm hardened and then annealed silver steel. I set the speed to 16 000 rpm and took the first cut at a depth of 0.2mm without problems. Having raised the cutter I went back to the start to make a second cut at 0.2mm deep. The cutter broke  :( I put in a new cutter and tried again at 0.1mm depth and finished the initial slot in 0.1mm steps. The slot was then widened also in 0.1mm steps. The finished slot looks good but I am not too sure why the cutter broke on the second cut  :headscratch: The initial cut wasn't really 0.2mm deep due to the curvature of the rod, maybe I was a little clumsy with the feed at the start of the second cut. This is the first time I have used a cutter less than 2mm dia.
Best regards

Roger

Offline Johno

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Re: Proxxon MF70
« Reply #8 on: January 07, 2018, 02:29:56 PM »
Hi Rodger,

I have had a MF70 for sometime. I find it superb for fine work. Like yourself I have also broken a 2mm cutter & blame myself for that as you need a very delicate touch as you approach the work piece. Also, I have found the importance of keeping gibs finely adjusted. I have the Proxxon Dividing Head that matches the machine which I find increases the M/Cs capabilities greatly.
 
I think some often criticise this m/c as they don't realise it is designed for very fine work.

Ian

Offline Roger B

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Re: Proxxon MF70
« Reply #9 on: January 09, 2018, 11:18:25 AM »
Ian, I agree this is definitely a second mill unless unless you are making really small models. I bought it with the expectation of needing to carry out some upgrades, but it appears fine as it is. I may still do the ER11 chuck mod as it is reversible and allows access to a wider ranged of cutters. I wouldn't consider using a 6mm end mill but there are a lot of small carbide cutters with a shank bigger than 3mm.
I have the dividing head and vice on order (out of stock before Xmas) and will add them to this thread when they are delivered.
Best regards

Roger

Offline Admiral_dk

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Re: Proxxon MF70
« Reply #10 on: January 09, 2018, 09:23:55 PM »
We use a good number of carbide drills 0.3 - 3.175 mm. and some mills 0.8 - 1.3 mm. with 1/8" shank for PCB routing. The absolute best I encountered are German but most Chinese are almost as good and very cheap + the collets are cheap too.

3mm. shanks are higher prices.

We either buy them on Aliexpress or eBay.de

Offline Roger B

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Re: Proxxon MF70
« Reply #11 on: January 16, 2018, 07:52:44 PM »
Thank you Per  :ThumbsUp: I was looking as some carbide round nose endmills from CTC which came with 4mm shanks. I do have a 3.2mm collet which will do 1/8" shank. I will have to look further.

I received the Proxxon vice and dividing head. The chuck on the dividing head seems smooth and the jaws do reverse. The Vernier scale is certainly good for 1° and I think it could do 0.5°. The vice is also nicely made. The only thing missing (to me) is a vertical V groove. It aligns nicely with the table and can also be held at various angles using the normal clamps.
« Last Edit: January 17, 2018, 07:27:15 AM by Roger B »
Best regards

Roger

 

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