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  1. #11
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 7 Hours Ago Has been a member for 4-5 years. Has a total post count of 964. Received thanks 162 times, giving thanks to others 5 times.
    Quote Originally Posted by hoppo View Post
    I could I suppose easily convert to direct drive later if backlash becomes an issue.
    There are plenty of us using belt drive without backlash issues. Properly set up amd with the proper belt/pulley combination, backlash isn't a problem with belts. I use two drive motors for the master and slave X axis ballscrews on my router with short belts but there are quite a few builders who have gone for one motor with a long belt which works fine. I think that you should make the direct/belt drive choice based on other factors. I went belt drive as it meant that my motors are tucked in inside the overall build envelope, I can change drive ratios if I need to, and I get a bit of isolation of motor stepping from the ballscrew. It's also easier to build and adjust mechanically. Direct drive means very careful alignment (even if you are using Oldham/Lovejoy/flexible couplings). Both are viable methods but be aware of all the trade-offs before deciding.

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  3. #12
    Quote Originally Posted by hoppo View Post
    Started construction of the Z axis front and rear plates. Armed with a hammer a center punch, a set of hss drill bits and a few counterbore bits off ebay and my trusty Clarke Bench drill this is the outcome.

    Attachment 21703
    Holes all marked out on the Z axis rear panel. This is the part that will attach to two ball screws and 8 bearings.

    Attachment 21704
    Drilling starts with earnest. Amazingly way easier than I thought it would be. I did use some cutting oil just in case and got a very good finish on the holes. Again as a newbie and not being too sure about my layout being particularly accurate I oversized the holes by 0.5mm to give me a little bit of wiggle room in case of alignment issues due to my possible dodgy setting out.

    Attachment 21705
    Finished drilling the holes on this plate. The larger holes are to take 10mm bolts to fit to the ballscrew block. Drilled at 11mm diameter.

    Attachment 21706
    The process begins again for the front plate that will hold the ball screw bearing blocks, spindle mounts and the supported rails.

    Attachment 21707
    More drilling.

    Attachment 21709
    The two plates with all the holes drilled. All look to be in the right place. I'm fairly happy with how fairly straightforward this was. It was working with aluminum that was most unsure about as I have no real experience working with it. It's just like drilling wood but smoother!

    Attachment 21716
    Countersinking of the holes to take the captive bolts that will hold the whole thing together.

    Attachment 21717
    The two finished plates, with all the holes in the right place and more importantly all the conterbores on the correct sides. There was a moment of panic when I thought I'd countersunk the larger holes on the wrong side but was relieved when checking the drawings that all was in fact correct. I did get some quite serious chatter whilst countersinking the larger holes. These are 18mm from memory and I had the bench drill on the slowest speed which is about 500rpm. I reckon it would have been better if it could have been slowed down a bit more. Anyway with plenty of cutting oil and only a little ringing in my ears afterwards I think I got away with it.

    I hope I didn't 'bore' you all to death with a post that mainly 'revolves' around drilling holes. My wife thinks I'm mental having spent a day in the cellar doing nothing but drilling. Personally I loved it and am feeling quite chuffed.

    I hope you found this post useful.

    Cheers.
    Nice work, I'm shitting making the mounting plates the plan was to pay to have them made but I have considered trying to make them myself by printing to scale on A4 clear sticky plastic sheets. Then sticking the plastic onto the plates and use a drill press. You're inspiring me ;)

    If I have them made I will have the mounts to the SBR made in steel and the mount for the z axis (Which will also be the z axis) from aluminium. Whatever happens I need to have the aluminium plate made as it will have 2 bearings pressure fitted fro the ballscrew so needs to be super accurate.
    Last edited by Desertboy; 18-05-2017 at 06:41 AM.

  4. #13
    Quote Originally Posted by Neale View Post
    There are plenty of us using belt drive without backlash issues. Properly set up amd with the proper belt/pulley combination, backlash isn't a problem with belts. I use two drive motors for the master and slave X axis ballscrews on my router with short belts but there are quite a few builders who have gone for one motor with a long belt which works fine. I think that you should make the direct/belt drive choice based on other factors. I went belt drive as it meant that my motors are tucked in inside the overall build envelope, I can change drive ratios if I need to, and I get a bit of isolation of motor stepping from the ballscrew. It's also easier to build and adjust mechanically. Direct drive means very careful alignment (even if you are using Oldham/Lovejoy/flexible couplings). Both are viable methods but be aware of all the trade-offs before deciding.
    I've scrapped quite a few commercial printers over the last 5 years and I keep seeing the same thing, the main drives are direct drive by either ballscrews or often leadscrews. The ink is always delivered by nema 23 using belt drive with tensioners gearing to ~4 to 1. With a properly setup up belt tensioner I can see backlash is so slight as to be negligible. Thing is though making any system backlash free is a major hassle and even ballscrews exhibit backlash over time as the bearings wear unless using a 2 nut style system. The reality is though most people won't even notice minor backlash and if you can notice it then you have more than minor backlash lol.

    What put me off was the belt tensioner, it's easier for me to direct drive then belt drive.
    Last edited by Desertboy; 18-05-2017 at 06:38 AM.

  5. #14
    Quote Originally Posted by Desertboy View Post
    Nice work, I'm shitting making the mounting plates the plan was to pay to have them made but I have considered trying to make them myself by printing to scale on A4 clear sticky plastic sheets. Then sticking the plastic onto the plates and use a drill press. You're inspiring me ;)
    Ha, that's more or less exactly what I did. The quotes to have them made were coming in at silly money. I think one quote for the two plates was over 600. This forced my hand. I figured that two pieces of aluminium cut to size would be cheap enough. I think the postage almost doubled the price. I then printed the layout to scale on the wife's cheapo laser printer. Used parcel tape to stick it to the aluminium and centre punched through the paper. I was also shitting it about this but it was pretty straightforward looking back. I thought I had a photo somewhere of the paper stuck to the aluminium, I'll have another look see f I can find it.

    Click image for larger version. 

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    The marking out process.

    I reckon I could almost as easily have made them in steel if I had access to a better pillar drill and took my time with plenty of cutting oil.

    Cheers
    Last edited by hoppo; 19-05-2017 at 06:56 AM.

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  7. #15
    Quote Originally Posted by hoppo View Post
    Ha, that's more or less exactly what I did. The quotes to have them made were coming in at silly money. I think one quote for the two plates was over 600. This forced my hand. I figured that two pieces of aluminium cut to size would be cheap enough. I think the postage almost doubled the price. I then printed the layout to scale on the wife's cheapo laser printer. Used parcel tape to stick it to the aluminium and centre punched through the paper. I was also shitting it about this but it was pretty straightforward looking back. I thought I had a photo somewhere of the paper stuck to the aluminium, I'll have another look see f I can find it.

    I reckon I could almost as easily have made them in steel if I had access to a better pillar drill and took my time with plenty of cutting oil.

    Cheers
    The only reason I would have them made in steel is my mate has the equipment to do it and told me it's actually easier for him to do steel than aluminium.

    600 robbing bastards I was quoted 100 cash if I supply my material but I have less plates.

    The good bit is once we get our machine working if we ever want to make another one we can make our own plates on our machines ;)
    Last edited by Desertboy; 18-05-2017 at 08:41 AM.

  8. #16
    Quote Originally Posted by Neale View Post
    There are plenty of us using belt drive without backlash issues. Properly set up amd with the proper belt/pulley combination, backlash isn't a problem with belts. I use two drive motors for the master and slave X axis ballscrews on my router with short belts but there are quite a few builders who have gone for one motor with a long belt which works fine. I think that you should make the direct/belt drive choice based on other factors. I went belt drive as it meant that my motors are tucked in inside the overall build envelope, I can change drive ratios if I need to, and I get a bit of isolation of motor stepping from the ballscrew. It's also easier to build and adjust mechanically. Direct drive means very careful alignment (even if you are using Oldham/Lovejoy/flexible couplings). Both are viable methods but be aware of all the trade-offs before deciding.
    Thanks Neale, that's reassuring. My main reason for going belt drive was to increase speed with the 1605 ballscrews. I've ordered HTD5 pulleys with 9mm width and belts. I figure I'll just cut slots in the vertical mounts to be able to adjust by sliding the motor to increase belt tension rather than using a separate belt tensioner.

    Cheers

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  10. #17
    It's been a while since my last post, but things have moved on considerably. Here is the next installment of my build I hope you enjoy.

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    Fashioning a bracket to hold the stepper motor at 90 degrees to the ballscrew. This is where I drilled the holes. The aluminium was precut from the supplier.

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    After a bit of countersinking and filing I managed to get it to look like this.

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    For some reason, after assembling it became apparent that it wasn't necessary, but after a lot more countersinking and some dodgy radial loads being applied with my pilllar drill, brute strength and plenty of ignorance I achieved my aim of countersinking the slots to sink the stepper motor holding bolts into. It's not the best looking piece of metal work, but I guess that's why I'm building the thing anyway! It should do the job.

    Click image for larger version. 

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    After marking through the holes on the stepper bracket mount with a transfer punch, I drilled them with a tap drill (4.2mm) for an M5 tap. This was the first of many taps. My advice to anyone attempting their own build is to buy a decent tap wrench and set of taps. I started off with the one seen here which came as a set with a set of taps and dies. It was bloody hard work, the handle kept falling off and eventually later on a cheap tap snapped off and remains in a hole on my build. I paid out for a snap on M5 and M6 tap and tap wrench. Probably cost the best part of 30 but one of the best purchases in hindsight and made the build a hell of a lot easier. As you'll see later there are plenty more holes to be tapped yet.

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    Attaching the spindle brackets to the front plate of the z axis. Again in hindsight this isn't the best design as the bolts holding them on are inaccessible from behind once the rails are attached. Eventually I'll get round to turning the bolts around and using captive nuts on the back side. I would have liked to have drilled the holes and tapped them but cannot get the accuracy right without the use of a CNC machine. Chicken and Egg comes to mind.

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    The front of the spindle brackets attached. Just because I can.

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    Linear bearings attached to the rear plate of the z axis.

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    The linear rails attached to the front plate of the z axis.

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    And the ballscrew also attached to the front plate of the z axis.

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    Rear plate and front plate of z axis married together and working well.

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    As above but from a different angle.

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    Attaching the stepper motor holding bracket to the top of the front plate.

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    Final assembly of all components of the z axis. All in all fairly straightforward. As mentioned above the hardest parts were 'milling' (repetitive drilling and filing) out the slots for the stepper motor and tapping the threads with the worlds cheapest tap wrench and taps.

    Plenty more to come. I hope you find it useful and or interesting.
    Last edited by hoppo; 13-08-2017 at 03:23 PM.

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  12. #18
    How much Z travel have you aloud for? Its unusual to fit the motor on the spindle plate
    ..Clive
    The more you know, The better you know, How little you know

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  14. #19
    Quote Originally Posted by Clive S View Post
    How much Z travel have you aloud for? Its unusual to fit the motor on the spindle plate
    I had to take a 2nd look at his cad model at the beginning of the thread to see what was going on, the nema is a dual shaft nema sticking through the end of the plate and then belt driven.

    I'm sure you saw this straight away but it confused me lol.



    Looks like the travel is quite small.
    Last edited by Desertboy; 14-08-2017 at 07:55 AM.

  15. #20
    Quote Originally Posted by Clive S View Post
    How much Z travel have you aloud for? Its unusual to fit the motor on the spindle plate
    Hi Clive, total travel on the z axis is just over 3 inches. Or 8 cm. this was the most I could realistically squeeze out of it due to the length of the z axis rails, also I wanted to keep the bearing blocks as far apart as possible to maintain rigidity of the z axis in both the x and y planes. I mentioned in an earlier post that one of the regrets I had was buying the rails and ballscrews and designing my build around those, rather than designing my build and ordering bespoke lengths to suit. Hindsight hey? Still 8cm is more than adequate for my needs at the moment.
    I have loads of spare travel on the z axis ballscrew so I figure I could expand the z axis travel if needs be by adding longer rails which would hopefully not be too much of an expensive upgrade.
    I can't remember the exact reason I chose to fit the stepper motor on the moving face of the z axis. I have been working on this design and build for best part of 5 years I reckon now. I'm sure there was a valid reason but can't for the life of me remember why. I put it down to age. I'm off to rack my brain and figure out what I was thinking at the time and what my reasoning was!
    Last edited by hoppo; 14-08-2017 at 08:35 AM.

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