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  1. #201
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    Jun 2011
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    0
    just curious as I'm using my phone to view this....and well done nice update..but I can't make out from my phone but is that two timing pulleys or a narrow belt on one pulley
    Eoin

  2. #202
    I ran the motor again for about an hour starting at 50% and working my way up to 100% in 10% steps. The motor seems better, but the main improvement seems to be the higher rpm of the treadmill motor(6000 vs 4000). I was able to cut a .375" wide by .060"DOC slot at 36IPM and 6000RPM in aluminum with the new motor.

    After playing with it for a while I did some test cuts with a 3F .1875" end mill. I found that .090" DOC at 27IPM/6000RPM worked pretty well when doing my test cuts on slots .270" deep. So I tried cutting a batch of parts with those settings. What I found is that after 5-10 minutes the mill would load up and break. I tried increasing feed, decreasing RPM, decreasing DOC, etc. I finally came to the conclusion that I'm just putting too much heat into the tool and eventually it starts to chip weld. You could see the chips welded to the sides of the slots got worse as time went on.

    I really don't want to deal with flood cooling so I dug up some info on builting a zero fog misting system(AKA Fogbuster) and ordered all the parts I need to build one. The parts should be here on Monday. Hopefully I can get it up and running and get back to cutting by Wednesday night.

  3. #203
    Mad,
    It's a 1/2" belt on a 3/4" pulley. I bought 2 of them before I realized that they were too narrow. I honestly doubt my current setup will overtax it though.

    Chris

  4. #204
    Janice584
    Guest
    I finished the base plate for the treadmill motor tonight. I'm pretty happy with the way it came out.

  5. #205
    Deleted...

  6. #206
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    Jun 2011
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    Quote Originally Posted by ChrisAttebery View Post
    Mad,
    It's a 1/2" belt on a 3/4" pulley. I bought 2 of them before I realized that they were too narrow. I honestly doubt my current setup will overtax it though.

    Chris
    yeah I thought it looked like a half inch and that's the belt width I'm using too and I've been running my spindle at 3,800 rpms for long runs, and the belt gets warm but I've had absolutely no problems with it like jumping teeth or the likes...and so if you were a little bit concerned about the width.....no need it works fine
    Eoin

  7. #207
    I'm really not worried about it. I'm only getting a MRR of around .81 with the treadmill motor at 6000rpm. That's only about .3hp so I don't think I'm pushing the belt too hard. I'm hoping that the addition of the coolant system will allow me to push the cuts a little harder.

  8. #208
    BTW: I'm not that happy with the pulleys that I had machined. They both have enough run out that you can see it (~.0010"). At ~3000rpm the vibration is not too bad, but as I increase the speed above there it gets really noisy. I don't have access to a lathe right now so I'll just live with it. I'll do all my roughing at 6000rpm and slow down to 3000rpm for finish cuts.

  9. #209
    I got all the stuff for my mister system on Tuesday. I used Karl T's basic idea with the tank at a higher pressure than the air line. I have a regulator on my compressor that I set to 40-60psi. That goes straight to the tank. The air line has a separate regulator that I set to 10-20psi. This way you have positive pressure on the coolant and it doesn't get atomized so there is no fog. I tried a .040" nozzle, but it didn't have as much air volume as I'm used to and I'm afraid it might not clear the chips very well in deep slots. I'd like to try .060" like the air blast nozzle I was using before. The nice thing is with the dual regulators and needle valve for the coolant you can adjust the mix any way you'd like it. I picked up a Loc-Line kit, so I'll replace the brass tube soon.

    I also picked up some end mills from Mari Tool to try out. I thought I would try using a 3/16" 3F Rougher for aluminum to do my deep slots. Hopefully they will do a better job of clearing the chips.

    I'm going to be busy the next couple days, so I'll do some testing over the weekend when I get a chance.

    Chris

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  10. #210
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    Join Date
    Feb 2011
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    605
    I have the same issue with a .25" 3 flute tool and those same feeds.

    People say its the 3 flutes. I'm switching to 2 flutes.

  11. #211
    jid2,

    Let me know how it works out for you.


    Chris

  12. #212
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    Jun 2011
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    0
    I just posted in jid2's thread too but also don't take my word as being the answer either. ..... but for me as I don't have an air compressor only a 12VDC marine bilge pump submerged in my coolant tank..... I use flood coolant all the time and even using a four flute endmill I can achieve fairly good cutting speeds with slot cutting....so it might be another solution to look into
    Eoin

  13. #213
    Yeah, I was hoping to avoid flood coolant. I have a friend with a Tormach who used to make all my parts and used to own a CNC shop. He never uses anything but a Fogbuster, so I am hopeful that I can get away with it too.

  14. #214
    Gold Member
    Join Date
    Nov 2009
    Posts
    4392
    I love flood.
    A lazy man does it twice.

  15. #215
    I was finally able to test out the mist system today. The .040" nozzle cooled the cutter fine, but it didn't clear chips at all. I took the tip out to .060" and it worked better. I wound up using 50psi on the coolant and 35psi air. I attempted the 3/16" slots again at 6000rpm. 24ipm and .090" doc was too aggressive so I went with 18ipm and .054" doc and that worked out great. I think the feed is pushing the tool harder than the doc. So I'll try .068" at 18ipm for the next batch.

  16. #216
    I've come to the conclusion that small 3F end mills are a PITA for slotting even with mist. Yesterday I bought a couple 3/16 2F Best Carbide AL end mills and ran them in the same slotting operation I've been struggling with for the last couple weeks. I was able to run the slot at 30IPM/.054"DOC/6000RPM and the end mill was throwing 90% of the chips clear of the slot even at .270" depth (1.5x diameter). I'm much happier now.

    I've also come to the conclusion that my treadmill motor is pretty weak. I could see one of the brushes arcing pretty bad (blue) during those cuts last night and that was only a 1/10th HP cut. The com is clean, the brushes look OK and the springs feel decent. I think I'll just order a new motor and get it over with. :tired:

  17. #217
    Well, I think the motor is bad. I'm giving up on this one. I was trying to cut AL at 6000rpm, 36ipm, .375"x.055" and it was arcing terribly and smells like burnt electronics.

  18. #218
    I won a brand new motor on Ebay for $93 the other day. It has the same specs as the one I already have, so I'm interested to see if it has any more power. In the meantime I put the stock motor back on the machine to finish up a batch of parts.

    I also had another problem with chips getting on the Y screw when the table is all the way back. It has bugged me since I bought the machine that the screw was exposed like that. I had a sheet metal shop make me a shield for the front of the table. It is 6" deep and runs the full width of the table. It should prevent any more chips getting on the screw, ways and homing switch. I'll post a picture when I get it installed.


    Chris

  19. #219
    I received the new motor on Saturday. I got it installed and ran some test cuts with it. With a 2F carbide .375 AL end mill turning 6000rpm I was able to go up to .100" DOC at 30IPM, but the cuts looked rough any deeper than .060". With a 3F .375 I was able to cut cleanly at 45IPM and .060". To me the G0704 just isn't stiff enough to push much harder than that. For production runs I'll stick to 2F/36IPM/.060 or 3F/45IPM/.050".

  20. #220
    Chip shield installed:
    Click image for larger version. 

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