how straight

This topic contains 8 replies, has 3 voices, and was last updated by Profile photo of SteveC SteveC 1 year, 1 month ago.

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  • #4629
    Profile photo of umashankar
    umashankar
    Participant

    how straight must these tubes be. I live in india and can get thin walled stainless steel tubes, but I am not sure they will be dead straight. is there a simple way of straightening them if they are not.
    (almost finished printing all the plastic parts in abs)

    umashankar

    #4631
    Profile photo of vicious1
    vicious1
    Keymaster

    I am not sure how to answer that. Nothing is perfectly straight, you can always turn the bend until it is facing a direction that matters less.

    I boils down to how perfect do you need the machine to be? are you going to be cutting PCB’S? Around here we get hardware store electrical conduit and it is definitely not perfect and usually to even perfectly round. You would be surprised at how far off it can be before it actually matters.

    Be careful with that ABS I don’t think very many people have had much success printing the parts accurate enough. ABS shrinks. I do not use ABS there are many other materials that hold dimensional accuracy much better. I think PLA is the best, its shortcoming is its heat tolerance which doesn’t matter in the CNC, second choice is any form of PET.

    #4686
    Profile photo of umashankar
    umashankar
    Participant

    thanks. I was thinking of pcbs, but will now probably use this to cut acrylic parts needed for a pcb machine (cyclone). Generally this is a way of staying young at 70.

    unfortunately I have printed more than half the machine in abs. I switched to abs because I had a lot of trouble making pla stick to the heated bed, but maybe I will try again. so far the parts look usable. I have just printed the four corners and the sliding x and y.

    umashanks

    #4688
    Profile photo of vicious1
    vicious1
    Keymaster

    If you are worried about it being straight just make it small. You will be able to handle PCB’s no problem if that is your intent. I worded it that way because Most people say they want to mill full sheets of plywood, some aluminum, and pcb’s. Sorry, I don’t know of any machine that can do that well. If you are just trying to do PCB’s make it small and you can easily dial it in.

    As for the PLA a heated bed isn’t usually needed. I set mine to 40C and use blue painters tape wiped with high proof rubbing alcohol. It sticks so well I need to soak them in the alcohol to get the tape back off.

    #4691
    Profile photo of SteveC
    SteveC
    Participant

    My solution for PLA on glass is: evenly spray Aquanet Extra Super Hold on the room temp bed, heat bed to 60C to dry it fast, then print at 50C or so.

    That said, I did print my Middle_Joiners in ABS and they worked just fine. I use the above procedure for ABS but print with the bed at 110C and use some aluminum foil to keep the heat in. For PETG I do the same as ABS but keep the bed at around 80C. For all plastics, ABS, PLA and PETG I use a 3 or 4mm brim to help adhesion.

    #4704
    Profile photo of vicious1
    vicious1
    Keymaster

    I used to use aqua net but always needed at least 8 coats to get a good base layer. after that I only would need to give it a light coat between prints. After a year of printing though it made my printer super nasty so I chose not to spray any of the new printers with it.

    #4710
    Profile photo of SteveC
    SteveC
    Participant

    I use a shirt box bottom with a rectangle cut out to shield the rest of the printer from overspray. I’m also a bit OCD about it and clean off the build plate with water or wood alcohol between prints. So I only have one layer of Aquanet. I never even tried painter tape.

    #4711
    Profile photo of vicious1
    vicious1
    Keymaster

    1 layer? I tried the spray shield but got tired of moving the z out of the way. I will try this again for sure because the prints stuck perfectly, came off easy, and left an amazing surface finish. That is when I made the robo spool hold on thingiverse and the bottom surface was actually the pretty one.

    I used to put it on hot, maybe that is why 1 layer wouldn’t work. off to the store to confuse the cashiers by buying 3 bottle of hairspray!

    #4716
    Profile photo of SteveC
    SteveC
    Participant

    The problem with spraying it on hot is that it would dry instantly in uneven dots. If you spray on cold the amazing Aquanet gets a chance to flow and evens out to a perfectly flat surface.

    1 layer means one thin coat. Yes I always feel funny at the cashier buying the cheapest hairspray on the shelves 🙂

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