509,965 active members
3,418 visitors online
Register for free
Login

Search:

Type: Posts; User: peteeng

Page 1 of 20 1 2 3 4

Search: Search took 0.01 seconds.

  1. Replies
    7
    Views
    4

    Re: crane style cnc machine

    Hi Dingo - I think you need to rethink the config. To move radially 0.25mm at 6m radius requires a move of 0.00119deg. If you used a std 200step stepper this would require a gearbox with a 1513:1...
  2. Re: Moving table (fixed gantry) with two ballscrew

    Hi Ivan -Thanks for offer but yes its expensive Europe to Oz. I found some milled carbon fibre in france that I wanted. 20 euro/kg for the sample and 180 euro to get it here. I'll have to wait until...
  3. Re: Moving table (fixed gantry) with two ballscrew

    Afternoon here Ivan :) Good keep us up to date. I too am re starting a moulded cnc mill design so thanks for your help so far. I'm trying to get the biresin here in OZ but seems sika don't stock it...
  4. Replies
    3
    Views
    4

    Re: Two Axis CNC Table

    Hi Agaylor - I suggest you use belts in such an application. A 10 or 16mm AT belt would work fine. Use 15 or 20mm rails and cars and NEMA 17 or 23 steppers. Depending on the speed / acceleration you...
  5. Replies
    7
    Views
    4

    Re: crane style cnc machine

    Hi Dingo - You will have to find a clever maths person who can do a jacobian transfer of the co-ordinates so a std 3 axis system output can be translated into the cylindrical co-ords of your system....
  6. Re: Moving table (fixed gantry) with two ballscrew

    Hi Ivan - Yes segregation is a big problem when aiming at high packing factors. More reading this morning and most concrete mixes in reality are about 70% Vf maybe 75% in the lab. The theories that...
  7. Re: Moving table (fixed gantry) with two ballscrew

    Morning Ivan - So what are you aiming at? Industry information tells us that 70%Vf is about the top figure and you have achieved that. Are you chasing 90%? Industry has settled on 70%Vf for a reason....
  8. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    Hi Buoyen - 400 is a bit thicker than many out there. But it will work. Look up Biresin CR83 via SIKA. 155 mpas and longer gel time. The longer gel time allows the resin to wick into corners and...
  9. Re: Moving table (fixed gantry) with two ballscrew

    added the resin data sheets - Peter
  10. Re: Moving table (fixed gantry) with two ballscrew

    Hi Ivan - some updates on the quartz stiffness now some groundwork has been done. I have always thought quartz was E=70GPa but seems being a crystal it is anisotropic (always a fly in the ointment)....
  11. Re: Moving table (fixed gantry) with two ballscrew

    Morning Ivan - Your doing fine with your english and the tests. When you quote a ratio or % always state whether its by weight or by volume so others know what you mean. Also as a note you will...
  12. Re: Building Steel Frame Gantry Router for wood, MDF, and maybe more

    Hi Machine dud - any photos, we like to watch. Yes I have discussed lots about bolts, rivets, brazing and other ways to build machine frames. The friction in bolted joints make it damper then a...
  13. Re: Moving table (fixed gantry) with two ballscrew

    Hi Ivan - Here's the rub with packing. If we look at a 2D representation using spherical particles we get a possible 2D packing factor of 91% and in spheres 3D it's a bit better. But clearly no one...
  14. Re: Moving table (fixed gantry) with two ballscrew

    Hi Ivan - I would stay in cast epoxy world or steel world. The tube inner will vibrate and being stiffer then the casting may be the dominate structure then you may as well have fabricated it. If...
  15. Replies
    45
    Views
    361

    Re: Jake's 4x8 CNC Build

    Hi Jake - Thats a good question and can't be answered without some calculation. Machine stiffness is measured in two ways: static and dynamic stiffness. Dynamic is difficult to measure but very...
  16. Re: Moving table (fixed gantry) with two ballscrew

    Ivan - I don't think you need strength you are chasing stiffness. Rebar is added to concrete to improve tensile strength and to create a loadpath thru the concrete when it cracks which it does and...
  17. Re: Moving table (fixed gantry) with two ballscrew

    Hi Ivan - Yes avoiding the welding etc is worth doing. The 18GPa is not a big issue as long as the members are big to compensate. You are taking advantage of shape in a moulded part so maximise the...
  18. Re: Moving table (fixed gantry) with two ballscrew

    Hi Ivan - The epoxy ratio is dependent on the density of the constituents and the volume ratio achieved in the pack. If you have done any concreting you will know that when you vibrate your mud the...
  19. Replies
    45
    Views
    361

    Re: Jake's 4x8 CNC Build

    Isn't the relieving counter productive in the stiffness dept? Stiffness comes before weight in importance? You are better to go to a thicker aluminium plate to get the weight loss and the stiffness...
  20. Re: Moving table (fixed gantry) with two ballscrew

    Hi Ivan - I'm about to make some epoxy aluminium slabs. See data sheet for powder. Quartz density is 2650 and aluminium is 2700kg/m3 say effectively the same. This powder has a bulk density of...
  21. Re: Moving table (fixed gantry) with two ballscrew

    Hi Ivan - CF instead of aluminium for some parts. Remember to do a dry fill and weigh then add water to figure out your epoxy ratio. 10% sounds too little for quartz. More like 28% by weight at 50%...
  22. Re: Request for feedback on a 4/5th axis for a CNC drill

    Hi Vum - You may not have enough teeth engaged to transmit the full torque. The mechtrol design doc has guidelines for teeth engagement. You also may need a tensioner. I've found you can't achieve...
  23. Re: Moving table (fixed gantry) with two ballscrew

    Hi Ivan -There are two concepts with machine bases. 1) That the stand is part of the structure of the machine and needs to be firmly integrated with it 2) That the stand is a stand only. I think...
  24. Re: Y Slave axis = A axis judders and doesnt work as good as others

    Hi Adam - Sounds mechanical. Have you really checked the mechanics are all OK? On my machine this has happened and it turned out the grub screw on the motor shaft was loose. Since then only use...
  25. Re: X Axis; 2 ball screws, 2 steppers or belt drive from 1

    Hi Kevin - Don't be shy no such thing as too stiff. And cost on a flat part vs material is small 1/2" or bends. Peter
Results 1 to 25 of 500
Page 1 of 20 1 2 3 4