Effer, a spare parts story.

Discussion in 'CNC machining projects' started by BattyZ, Jun 21, 2021.

  1. BattyZ

    BattyZ Copper Banner Member

    With all the head bangin' we are doing, we should be in a rock band, lol. Thanks for the kind words though. Eventually, I will get something to work, just how many of my brain cells will be left?

    I am using SuspendaSlurry for their nonferrous applications. To be fair I think the fault is all mine. The last time I did shell I let the kiln get up to 1800 and bake through. This time I only did 1500 which I am calling now is no-where-near-close.

    Speaking of moving forward, is your "dip-coating" pretty watery?
    20210815_155757.jpg
    After I watered the drywall mud down and dipped the mold, this is the result I got after brushing because it was quite thick in some areas and thin in others. I feel like I need to water it down a bit more. I also sprayed the foam dawn+water spray bottle as you advised.
     
  2. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Yes, to get the best result with just thinned drywall joint compound, I had to thin to the degree two dips were required but did produce a nice uniform coating. See here.

    http://forums.thehomefoundry.org/index.php?threads/dip-coating-polystyrene-foam.573/

    The commercial refractory coating I use dries quicker, stays in suspension longer, and self levels better. I stopped experimenting with the drywall dip coating but in addition to a little dawn soap mixed in, it would likely be improved by something to help keep things in suspension. Dextrin was used in some other formulations I read about but that is organic and can grow mold over time. A small addition of bentonite may also be helpful. Best advice for just thinned joint compound would be add a little dawn and dip immediately after mixing. I can send some of the other recipes if you're interested.

    31 Mud.JPG

    Don't know that it makes much difference other than being the non-setting variety but this was my flavor of joint compound.

    Best,
    Kelly
     
  3. BattyZ

    BattyZ Copper Banner Member

    All good info. I will try a little bit of bentonite and dawn soap. The post says you did a dozen or so drops of dawn. What kind of percentage should I aim for in bentonite?

    Also thinking about this, I should try just one coat of the Suspenda Slurry with no sand and see what that yields.
     
  4. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    It takes a shockingly small amount of Dawn.....like a teaspoon per gallon.

    This I cant say for sure, and it's just and educated guess, as I see it typically used for binder in various coatings and slips. Also depends on whether its sodium or calcium bentonite but in any case, I'd start with 1%-5% by weight.

    I honestly can't say. Although I have it, never tried it for LF. Even though shell is permeable, my sense is it would be less permeable than mud or the commercial coating only because it seems to be quite a bit more dense......but maybe not. One thing about mud and the commercial coating......it just falls off the casting where it seems shells adheres quite a bit more tenaciously.....but it's also been fired.

    First I'd suggest you mix up and experiment with a cup full and a small object until you find the happy medium. I spent little time arriving at the results in that link.

    It can be a little more labor intensive but nothing wrong with brushing, unless you have interior features you want to coat.

    Best,
    Kelly
     
  5. BattyZ

    BattyZ Copper Banner Member

    Machining of the cast 5 axis head went on without a hitch! I thought fate would slap me due to my just using the vise for work-holding. I programmed in light cuts at all went smoothly.
    20210818_154817.jpg Snapchat-1007226065.jpg Snapchat-135925434.jpg Snapchat-1506989567.jpg
    This T5 timing belt profile was a little tricky. Cost me 3 endmills, lol. Found a ramping, contour toolpath to run at 30% to get the job done. I think it turned out well. Fitment of the belt is most acceptable.
    20210819_151008.jpg
    Head operation is MUCH tighter butttttttttttt there is still some play in the main C axis bearing. I think this play is inherent in the bearing and more of a design flaw. The final iteration will have a set of angular contact bearings. However, this setup will work for me for now.

    Oh here is a video explaning my multi-material journey:

    20210819_140314.jpg 20210819_144840.jpg

    Onto the 2nd problem: Kinematics and Post processors!
     
    Last edited: Aug 20, 2021
    jgro, Bldr J, Al2O3 and 2 others like this.
  6. Peedee

    Peedee Silver

    Very cool!
     
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  7. BattyZ

    BattyZ Copper Banner Member

    Bad day yesterday: remember when I said I needed to sort out the wiring on the head?
    20210907_105344.jpg
    The head was completing a 180-degree rotation when it just stopped and disconnected from my host pc. From what I can tell the B-head limit switch either shorted to the ground or shorted to my DC spindle power wires. The current spike shot right through the (now blown) resistor and did not-good things to everything upstream. Currently dead in the water.

    Silver lining: I was on my 3rd post-processor and finally had a pretty good working solution going.

    Moving forward, I will reorder another Kmotion board but will also order their Konnect board which optically isolates inputs to the mainboard for such situations like these. It will be a few weeks for this. In the meantime, I may go back to my 3 axis setup and a fixed head so I can be machining foam for castings. It will also give me time to redo my electrical cabinet and head wiring. Also, ponder the solution to the play in the main C axis bearing.
     
  8. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    That cogged head is a nice piece. Was the aluminum recycled material? I ask because I wondering if you heat treated it or how it machined. As cast, they can be pretty soft and gummy, and load cutters........but then in the video kind of fly right by when you say "I've got my rebuilt and working 95 Hitachi Seiki machining center"......that's a nice shop toy. Having cutting fluid helps but won't eliminate the gumminess. Tempering can make the part considerably stronger, harder and machine better, but aluminum can also tend to be a bit springy and vibrate/resonate but depends on mass and load. I couldn't tell the type of bearings but if they can be preloaded it will reduce the radial clearance and improve the positional accuracy.

    What a bummer. But, can't keep a good man down.....soldier on!

    Best,
    Kelly
     
  9. BattyZ

    BattyZ Copper Banner Member

    Thanks! I was happy it turned out. It is recycled metal. I typically try to water quench early after the casting. Normally I do a T5-ish heat treat but this time I did not due to time restraints and being antsy to see if the toolpaths would work. Had I loaded up the cutters I would have gone back to heat treat.

    It has been...once I got it working. I bought the best that I could afford, aka $500 11,000 lb paperweight, that had not run in over a decade. Took half a year to get it to move. lol I could do a post about it but I know that not everyone else has the time, resources to have a big machining center so I really didn't want to harp on it too long. I really should be making more use of it. The gallons per minute flood coolant helps greatly with gummy materials.

    Yeah, I agree. I really think this calls for a redesign where there are opposing angular contact bearings where one could set precise preload.

    With the main board going out it has really forced/allowed me to rethink some things for better success moving forward. So why I wait till the next one arrives and I can make some moves for the better.
     
  10. BattyZ

    BattyZ Copper Banner Member

    I have a little bit of a stay-cation coming up. Going to get this CNC router back up and running but only in 3 axis mode for now. Have some LF castings that need to happen and should be able to halve my CAD models.

    Been thinking long and hard about a cutting head design with double bearings that keeps wires somewhat managed. Looked into using a steering wheel "clock spring." Implementing 2 offset 45 degree angles for joints instead of 90's. Whatever I come up with still puts a lot of weight and or movement in the head. So I have started leaning into table-head setups. This would put one rotary on the table and keep one in the head. It would solve most if not all my cabling dilemmas. It's not that a little wiring problem is holding me up, it's more of the fact that eventually if I stay on this path the wiring will "bite again" and it will most likely be when I have a paying project on the line.

    The design that is currently winning would be keeping the B axis rotary still up on the Z axis. Then moving the C axis rotary to the table. If done correctly I could gain way more range on the B. The C axis would be fully continuous with a static stepper motor, big fan on this. The Z axis would be lighter/faster. One downside that comes to mind is that my fixed gantry legs would limit how big of a part I could rotate between them. Might be able to skirt this issue sometimes with clever CAM or setup.

    Anywho, I wanted to post my current plan to see if anyone had any ideas or comments that they cared to share.

    Thanks in advance!
     
  11. BattyZ

    BattyZ Copper Banner Member

    Just wanted to post a little update. Effer is back up and running on 3 axis LinuxCNC. spent some time tramming up my old router spindle and correcting machine skew but got quite a bit of foam routing finished. I have a Z-axis plate in the works to stiffen up the way long vertical travel. Designs are underway for the table rotary C axis and head tilting B axis setup. Also, I ordered a hybrid servo for the Y-axis to test out an option for closed-loop motors for all 5-axis.

    Snapchat-1597837887.jpg Snapchat-570431913.jpg 20211006_105444.jpg 20211006_102944.jpg

    This might be a little threadjacking myself but the wedding swords turned out...well kinda. I fudged up the feeding system, went way too big, handles were sized for giants, and I rushed the dip/brush coating. Redo-ing them. But I got a best man out of the deal so they served their initial purpose.
    Snapchat-987658633.jpg Snapchat-621652526.jpg
     
  12. DavidF

    DavidF Administrator Staff Member Banner Member

    Hmmm, someone needs a vacuum cleaner :D
    Looks good!! What did you use for the cam??
     
  13. BattyZ

    BattyZ Copper Banner Member

    Haha actually have a HF dust collector just out of the picture. Use it periodically. An enclosure is on the list but not going to let it keep me from casting!

    I use Inventor with their built in cam. Made small tweaks to the generic linuxcnc post processor for my specific setup back in '18.
     
    DavidF likes this.
  14. BattyZ

    BattyZ Copper Banner Member

    Was just wondering Kelly, what do you use for a heat treat or temper cycle?
     
  15. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Except in rare instances, T5 because it is all a precipitation schedule and the tolerances for temp, time, and cooling are very easily managed in a home shop. The time and temp will vary from different sources but 440F for 8hrs is typical. Cooling doesn't matter. This applies to 356. On critical parts I'll also add Strontium and TiB.

    Compared to T6, T5 achieves 75% of the strength and 85% of the hardness, but without the risk of melting or warping the casting. The solution cycle in T6 requires ~1000F for 12hrs and then a water quench but it can be quite difficult to control that in a kiln with high radiation. When I have done so I placed the parts inside a can to act as a shield from the radiant heating elements. The parts can also require fixtures to avoid warpage, especially during quench as they are weak and subject to handling damage as they are very near hot short condition.

    If I wanted/needed the extra strength I'd probably choose an alloy with better as cast properties like AlMag 35 (535).

    Best,
    Kelly
     
  16. BattyZ

    BattyZ Copper Banner Member

    I will do this with my next round of parts. Great information. I was doing 2-4 hours at 1,000F then quenching in boiling water but as you said....difficult. The parts I was heat treating were thick and quite self-sustaining during the process. I now have some parts that would be quite prone to warpage.

    8 hours at basically oven temps could be very hands-off. As far as my programmable kiln goes anyway. With appropriate kill/run-away switches and the like.
     

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