1. #1
    cncJim's Avatar
    Lives in Reading, United Kingdom. Last Activity: 2 Weeks Ago Has been a member for 3-4 years. Has a total post count of 170. Received thanks 15 times, giving thanks to others 32 times.
    Hi All,

    I am trying to find where to buy some HHS downcut endmills. My google skills seem to be failing me :(

    Found some nice carbide ones here:-

    But was looking for a HSS version?


  2. #2
    Sorry about the late response. Are you looking for left hand spiral end mills? In fact the full description is right hand cutting, left hand spiral. Down-cut is not a common description.

    A left hand spiral would be used to force swarf downwards, usually in profile milling, and particularly if you needed to force a burr onto the lower edge where plastics are concerned. Centre cutting isn't an option.

    As for where to find some, at an economic price, I haven't found a cheap or HSS option in the UK yet - sorry but my search skills are poor too. Uk sources may be limited to bigger manufacturers -we used them at work - in Carbide.
    Is this what you need?

    Good luck,

  3. #3
    cncJim's Avatar
    Lives in Reading, United Kingdom. Last Activity: 2 Weeks Ago Has been a member for 3-4 years. Has a total post count of 170. Received thanks 15 times, giving thanks to others 32 times.
    Perfect! Thanks very much for the link. Delivery is a touch expensive but the price of the end mills seems to make up for that.

    I am thinking of using them to cut dibond. Use a left-hand spiral to cut half way through and then use a right hand to finish the cut. hopefully leaving a nice finish on both sides.


  4. #4
    http://www.sorotec.de/shop/Cutting-T...ft-Mill-Tools/ These go up to 3mm on a 1/8th shaft. They might work out cheaper, I just buy from Roy Kloss without checking prices and delivery of others in Germany. You might find that an alu cutter gives you better results as it is designed to clear chips better. I have some dibond, I bought as a test piece for machining, but the project I bought it for never got off the ground so I have an A4 piece of red dibond in small sheet stock drawer. I didn't do any test machining on it apart fror 1 6mm hole.

    Cheers, Rob
    Last edited by cropwell; 30-01-2016 at 05:36 PM.

  5. #5
    compression cutters are expensive, but do give the best of both worlds. I don't know just how small they go down to, but I use a 6mm to good effect - certainly gives a good finish to both sides in a single cut. G.

  6. #6
    I keep thinking these would be good when I try to cut thin material, such as Formica or sub 2mm aluminium. The tool helix lifts it off the bed, sprays crut underneath it and everything goes to hell in a hand basket PDQ after that.Then I realise that this tool cannot plunge cut and quickly go off the idea.Am I missing something?

  7. #7
    Dibond is an aluminium sandwich with a Polyethylene core. The burrs you are looking to avoid are therefore aluminium - I bet it isn't a nice free machining variety either. The left spiral will push the burr from the upper surface downwards. I'm not sure how the reverse will work on the lower edge unless you can machine an offset to the profile - 0.1mm might do for example - to stop the second tool from rubbing the first, finished cut. It's CNC after all, and a CNC control should manage a profile offset.

    Do you have the opportunity to have a rigid sacrificial surface beneath the work piece? Are the edges supported well enough to be stiff and not flex in machining? Reply #6 points out the pitfalls accurately. Are your profiles much smaller than the raw material? Can you use tabs to stabilise the profile whilst clamping on the waste?

    One strategy that may help is to use fewer flutes - single flute cutters are good for plastic, I'm not sure about sticky aluminium. Also to avoid excessive spiral angles - the longer the tool edge in contact with the work piece, the more friction raises the temperature and melts the local area, pushing a bigger burr as a result. Straight flutes have the lowest contact friction. High spirals tend to pump swarf along the tool - the burr tends to follow.

    Can you get a good air blow onto the tool? Keeping things cool won't stop burrs but may reduce them, and it will reduce the chance for chips to link up and rejoin the cut.

    Good luck.

  8. #8
    Dibond can be cut in various ways but the bits that i like are 2 -3 flute straight ones or 2 flute fishtail 30degree spiral upcut which leave a mirror finish, and the bits originally meant to cut Dibond are single flute as pointed earlier. I know of only 2 ways to cut it properly:
    -vacuum bed
    -stick ultra thin strong double sided tape at least at the important points. Not the one they sell at stores. Best tape for purpose is photographic double sided thin tape used to bond methacrylate to photography. Its sold on rolls and 50m is 150-200 euro, but if you ask some sign shop for a meter it would last you months. Final pass should be no more than 0.2mm deep and slow as the tape is a bitch. So tape should be applied on small squares of 2-3cm here and there. Stick square bigger than 10x10cm and you will never unglue it, its so strong

    Possibly you problems with finish are from sheet flapping. With a sharp bit and air blown at the bit , when well fixed, you can cut it with speed of spindle for wood and say 1/3rd down the speed, at one pass/when vacuum table/.
    project 1 , 2, ...

  9. #9
    cncJim's Avatar
    Lives in Reading, United Kingdom. Last Activity: 2 Weeks Ago Has been a member for 3-4 years. Has a total post count of 170. Received thanks 15 times, giving thanks to others 32 times.
    Thanks for the contributions everyone.

    I ended up buying some 3mm up and downcut endmills from http://cnc-plus.de.

    Tried some some cuts on 3mm Dibond using a diy mdf vacuum bed and the results were great!.



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