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  1. #211
    Nice! It's very satisfying when the machine you have put so much time and effort into designing and building starts to produce that kind of output.
    An optimist says the glass is half full, a pessimist says the glass is half empty, an engineer says you're using the wrong sized glass.

  2. #212
    Seconded, that's a lovely piece of work.

  3. #213
    Tool deflection chaps, tool deflection!

    So I received a bunch of single flute endmills from China, these things cut aluminium and SRBP nicely. However I'm having some problems, and would like your diagnosis,

    So I've just cut a bunch of parts that need a hole that is a reasonable sliding fit on a 25mm shaft. I used one of my new 4mm single flute endmills, 2mm DOC, 1600mm/min into 10mm SRBP. It cuts like butter. However when I measure the hole afterwards it is larger at the top than the bottom by about 0.15mm, effectively the hole is tapered. If I cut the same hole with my usual 6mm 2 flute it is straight.

    I assumed this was the single flute deflecting on subsequent deeper passes but it could also be that the endmills are themselves tapered?? What do you think?

    I guess the solution is to rough with the single flute and finish with the 2 flute, just a bit of a hassle.

    Also could it be that i'm spinning them too fast a 24krpm and they are bowing out due to centrifugal forces?
    Last edited by devmonkey; 12-09-2020 at 03:46 PM.

  4. #214
    What happens if you take the feed rate down? And how long is the flute on the single? greater than the depth of the material?

  5. #215
    It improves somewhat with slower feed, the flute is longer than the material is deep. I just found one source of the problem the bolts holding the Y axis plate that ties the Z to the Y ballnut were not cranked down, they had worked themselves to just loose, nust have forgotton to loctite those one...

    Anyway this tidied up the top diameters which are now spot on again, but with the 4mm bit the hole bottom is still smaller than the top, error is much less, maybe 0.05mm. This is enough to be annoying as you get a decent H8 fit to the shaft on one side and but tight on the other, opening up the hole doesn't solve the problem as it becomes loose on the top. Doesn't matter at all for normal profile work just shaft and bearing fits. I will stick with the 6mm known quality cutters for doing these.

    I also just ordered a hopefully decent set of collets from Arc, not convinced by the much cheaper set I have based on the damage they take when you break an endmill.

  6. #216
    I've done some more experiments to try and determine the source of the non-vertical walls I get cutting SRBP with single flute endmills. I surfaced the spoil board and trammed the spindle before running these tests.

    In all cases the toolpath was a 25mm square in 10mm material, outer roughing profile to 9mm deep leaving 0.2mm for a single finish path at full depth.

    #1 4mm Chinese SF, 0.2mm taper top to bottom,
    #2 3.175 Chinese SF, 0.1mm taper top to bottom,
    #3 6mm Euro SF, 0.03mm taper top to bottom,
    #4 6mm Chinese 2Flute, 0.00 taper top to bottom.

    The taper is not constant, rather it bulges towards the bottom where the skirt was left to hold the part for the finish pass.

    I think that with this slightly flexible material the single flute cutters when slotting are leaving a slot smaller than the tool diameter, this is then cleaned up on the finish pass but not where the tool is cutting the skirt. The same material squeezing does not occur with 2 flute cutters. Has anyone else experience this with single flutes, I haven't noticed this happening in aluminium.

  7. #217
    I always find single flutes cut undersize. Never been sure it's a deflection or the tool. I always finish with a 2 flute and I also find HSS gives a better surface finish than carbide in aluminum for the finish passes.

    I hardly use Single flute cutters anymore. My preferred method is 3 flute carbide rougher leaving 0.4mm then 1x semi-finish pass @0.3mm and a final 0.1mm final finish pass. For work that doesn't need the best surface finish and accuracy I just take the full 0.4mm as a finish pass.
    -use common sense, if you lack it, there is no software to help that.

    Email: [email protected]

    Web site: www.jazzcnc.co.uk

  8. #218
    Quote Originally Posted by JAZZCNC View Post
    I always find single flutes cut undersize. Never been sure it's a deflection or the tool. I always finish with a 2 flute and I also find HSS gives a better surface finish than carbide in aluminum for the finish passes.

    I hardly use Single flute cutters anymore. My preferred method is 3 flute carbide rougher leaving 0.4mm then 1x semi-finish pass @0.3mm and a final 0.1mm final finish pass. For work that doesn't need the best surface finish and accuracy I just take the full 0.4mm as a finish pass.


    Hi Jazz, what 3 flute rougher do you recommend? I was quite looking forward to making less chips with these 1/8 single flutes but no point if you have to go around with a 6mm 2 flute to clean up,

  9. #219
    Quote Originally Posted by devmonkey View Post
    Hi Jazz, what 3 flute rougher do you recommend? I was quite looking forward to making less chips with these 1/8 single flutes but no point if you have to go around with a 6mm 2 flute to clean up,
    I mostly cut aluminum and use 8mm reduced neck Alu power cutters from cutwell tools, thou recently I've tried the APT version and they seem ok plus good price.

    https://www.shop-apt.co.uk/economy-3...-diameter.html

    I also tried these and they give a very nice finish, but I've not got enough time on them yet to see how well they last.
    https://www.shop-apt.co.uk/3-flute-v...lc-coated.html
    -use common sense, if you lack it, there is no software to help that.

    Email: [email protected]

    Web site: www.jazzcnc.co.uk

  10. #220
    Those look excellent value thanks. How deep DOC do you go with the rougher in ali?

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