Hoddem's DIY Linear Actuator

Looks really good @Hoddem all nice and compact and all sealed in. Not a death trap like mine

Impressive !

I have been printing parts non stop, so much so that I had to move my printer into the garage to keep the noise down. Everything is printed on my prusa I3 MK2S with 50% fill, Support enabled and using the 0.35mm fast option. I use Solutech 1.75mm silver metal pla at $17.99/kg


Here is the top part of the actuator printed in two parts to simplify the print operation. fairly lengthy print at 10+ hours. I design everything in Alibre and then port it over to fusion 360 to add the threads. I will some day convert to all fusion 360, but after so many years using Alibre its hard to dedicate the time to learn a new software.



I had a couple of issues with the design of the part, first the 12mm shaft clamps could not go far enough in and there was misalignment of the holes preventing the 12mm carbon fiber shaft from being inserted.



I filed down the printed part to gain a little more clearance, I also updated the model but at 10hours to print i decided not to print another.



Next the 12mm shaft clamps were protruding into the opening for the 25mmID linear bearing, per the models I was using I had clearance but the actual parts didn't. Rather then redesign the entire part I decided it was easier to file down the shaft clamps and make a flat spot, It only took a couple of minutes with a hand file.





Here is the finished part with the bearing pressed in and the reinforcement bolts added. Its pretty heavy and rock solid, I don't think it will have any problem supporting a horizontal load.




I have tweaked my supports to be a bit closer to the part so I no longer have perimeter lines out of place like I do here. They are a bit harder to remove, but seem to still release clean.

Here is the motor cover, the longest print I have ever done at almost 30 Hours and more than 1 lb of material. I had a panic attack at about 25 hours in when a storm rolled through and I was sure the power would flicker and kill the print.

There is a ton of support material in this print







The quality is ok, but not great. On all of my parts I am going for speed rather then quality, I may reprint everything at .2mm layer height once I have finalized and tested the design.

I have also been playing around with the idea of how to test this thing because I am getting very close to final assembly. I rummaged around to see what I had for extrusion left over and with what I have I came up with this for a test stand. Not sure how I would go about testing pull yet though, maybe hand the whole stand from the ceiling in the garage.



About the only thing I have for weights is a set of dumbbells at 55lbs each which I will fix to the free end of the structure, I will be able to vary the position of the actuator to increase or decrease the load.

thanks guys, I really enjoy this kind of stuff and I'm really trying to make this a clean and robust actuator. Hopefully it will perform well, be fairly low cost and easy to replicate.

Hi what motors did you use in the end?

Hi @Hoddem I know I have not been around for a while but DAAAAAAAMMM this is Great work . really impressed by what you have designed and achieved, even more so that your using a 3d printer to full effect .. this is crazy good stuff ... subscribed and will be watching this that's for sure ... I love the way the design builds in extra strength to the 3d parts , to think that a lot of these parts can now be done using 3d printer to me is mind blowing .....You've heard it before but can be said again Very well done. and nicely presented as well ..

This is the motor I picked up,
http://www.ebay.com/itm/1-hp-DC-12-...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
here is his website outside of ebay
http://www.hydrogenappliances.com/1hpmotor.html

I haven't done any testing yet other then hooking it up directly to 12v and checking the no load rpms.

It is also available in other voltages, I may go to 24V being that 12v*60a = 720w and would be pushing the limits of the sabertooth driver if it stayed at full load for an extended period of time. I know the sabertooth can drive 120a for a short while, but 24v may perform better overall.

The guy selling them has a few sample projects like motorized go-karts and bicycles, but it appears the main use is as a wind generator. Hopefully it will perform, I would hate to have to redesign everything at this point.

I see there are also a few other sellers selling the same motors now.

Thanks, It's nice to hear that people are interested in my project. I put a fair amount of thought into each part and what you don't see are the multiple re-designs I have already made to each part. I'm not sure if having a 3d printer has made me a better designer or a lazy one because I can print new revisions any time I want. I always seem to find some way to improve the design just about as soon as a part comes off the printer. I love cnc machined aluminum parts, but for a project like this it would be almost impossible to get it right on the first go and each revision would add a lot of cost to the project. I'm really starting to get a feel for what can be accomplished through 3d printing.

Hi Hoddem!
Wow!! I'm soooo impressed by what what you have done so far , and also your kindness for sharing your design!! thank you so much!!
I'm following you progress with passion and I can't wait to see this actuator finish and your final approve to get me started on mine

Thanks, I hope to get some more time to finish this thing up soon. So many projects and so little time.

I was always planning on using a 1" steering U-joint as my lower mounting method, but when I added it into my design I just didn't like it. I did a bunch of searching for "flange U-joints" and came across the website www.driveshaftparts.com. they have a pretty crazy array of stuff and I even found a few flanges that appeared to have a bolt pattern that matched my needs. I picked up a hand full of parts using the 1310 series u-joint.





Long story short the flanges didn't work out like I wanted so I decided to design my own using similar dimensions. So on the second revision this is what I ended up with.









I'm still using the 1310 U-joint, but I 3d printed the flanges. The flange that mounts to the actuator is now the end cap for the actuator and the bottom flange has hole spacing to mount to aluminum extrusion. I used some cheap u-bolts to capture the u-joint along with a couple of small screws to keep the u-joint from any side to side motion. It ends up being an extremely solid connection and extremely smooth because its using a real U-joint. I haven't measured the exact angle travel yet, but it looks like close to 45 degrees in all direction. All told this was actually cheaper then a 1" steering U-joint.

Here is a screenshot of how it interfaces with the actuator



Of course I did stand on it to test the strength and it feels rock solid. The unknown would be how much torque it can handle, but I'm assuming that it will be plenty strong enough for what I'm doing.

Parts were printed in PLA, 50% fill, .35 mm layer height

Jaw on the floor time cos @Hoddem You got skill my man ...dammm just when I think these dam printers are already good you go and do This LOL ...that is some serious work and I have to say in the best possible way , if this part can take the loads it will face then im upping my printer spec as its now moved into another catergory LOL. No in all seriousness if you print such a structural part and it survives then your now at excuse the phrase God level and I mean that as a compliment ....that is absolutely without a doubt great work...very well done ...the futures bright

You really rise the bar to the next level with this actuator! WOW beauty
I just wondering if the PLA will hold fine since it's a hard strong plastic but it's brittle more than PETG or ABS
I can t wait your load test if it's fine about that...personally I will print with colorfabb xt or taulman alloy 910
but hey I know it's not your final ... and PLA it's easy and cheap to print

Well done!
I can't wait to see some more update from you as always...

thanks

Thanks, that means a ton coming from you. In all honesty I have to give a lot of credit to my 3d printer, I picked up a Prusa I3 MK2S right after I started this project and It has been the best investment I have ever made. I have owned 5 different printers now and it is the only one that I can reliably print on day after day. Every other printer it seems like when I really need to use it I can't get the filament to stick or I need to re-level the bed 1o times to get it just right, the Prusa auto bed level just works and it has been printing non-stop since I bought it. My Monoprice Ultimate printer has been collecting dust ever since I plugged in the Prusa and it will probably be going up for sale because I just don't see the need for it anymore.

I highly recommend anyone looking at getting a printer to stretch the budget and go for the Prusa, it just works.

I have no affiliation with Prusa Research and purchased my MK2S with my own money at full price.

Thanks,

I actually was pretty unsure that PLA would be strong enough, when I started the design I did a lot of research into the various nylon and carbon embedded filaments thinking PLA wouldn't work.. I printed a lot of prototypes with PLA because that's what I had a bunch of and I figured after I got the design dialed in I would go back and reprint everything in something stronger. After I printed my first part at 50% fill I changed my mind about PLA. It kind of blew my mind how heavy and solid the parts were coming off the printer and I did the simple body weight test by standing on almost everything I printed in one fashion or another to see how much deflection I could get. all of my main structural components are rock solid and don't move at all under my body weight. I even removed all of the nuts from my design and printed the threads directly because of how strong everything was. That being said If there is one part I am concerned about it is the disk that supports the ball screw bearing.





Because of the way the bearing is inserted from the bottom all of the force will be across the 4 bolts holding it in and they are only 4mm bolts so in a way the entire actuator is supported by those 4 bolts, I may change the design to include hex nuts which would be plenty strong, but I want to see if that truly is the failure point or not.

I could also reverse the bearing, but that would eat into my stroke length and I would have to modify the 12mm shaft clamps for clearance. I could of course buy a longer ball-screw and shafts, but I am trying to keep the components as main source as possible and 500mm seems to be the standard for these components.

Hopefully I will get to test it out soon, I just picked up some wire to wire up the test stand. I don't have a good 12v source so I think I might have to get the jumper cables out and sacrifice my SUV battery.

I don't pretend to be an expert, but in this case I think I'd wimp out and play it safe by putting big washers & nuts on the other side
May not be needed, but it's not like those plates will be the easiest thing to replace if the tapped threads do fail.

That's how the design started, but removed all the nuts to reduce part count and simplify assembly. I want to test it out and see how it holds up, before I add them back in.

Here is the dilemma with flipping the bearing around, my shaft clamps will hit so I either file them down or raise them up. It would be a complete re-design of the plate to gain back as much of my stroke as possible. Ultimately I will probably go this route because it will be the strongest method, but again I will wait until I have some testing to prove its needed.