DIY Linear Actuator design

Hi Guys like Most here I have seen the great work done by @SeatTime with his 6DOF simulator and more importantly his design and work in making his own linear actuator , as you guys will have guessed by now I love a challenge and even though I was making good progress with my 6DOF simulator , I just knew SeatTimes actuator was something I just had to try to emulate , I take no credit for this Proof of concept project , but was hoping to see how cost effective and powerful an actuator could be built using mainly off the shelf items ...

Ok first off I did use my cnc machine to make some of the initial Feature but will be looking for Off the shelf substitutes once the basics of the design confirm if im on the right direction..

As with all my Tinkering please feel free to offer any design changes or mod, as this is a meant to be shared by our community, the Goal " a Cheapish -- er make that cost effective Linear actuator " for the Simulator Crew ..

Yeah Yeah I know wordy post but you guys get the jist, I have CAD drawing which I will post ( er there on my works PC lol ) but had a blitz this weekend and below are picture of the unit so far...

The 1st stage = Mechanical Assembly ( Copied from @Seattimes design then wannabeaflyered --tweaked to use materials at hand )
2nd Stage = Define driver / Controller ( SMC Ardunio, Sabertooth 2x32, 24Vdc
3rd Stage = load & speed testing (Option 1 Stepper Motor nema 23 Opt 2 Scooter Motor MY1016 2700Rpm 24Vdc 250 Watt? )

Seat time has defined what is workable , I tend to be suck it and see Developer ( behave guys keep it clean LOL ) ok ok change that to trial and error .

so this is the 1st post

Doh Specs lol,
the aim 350 -400mm actuator Travel
Speed >300 mm/sec ( dependent on motor choice )
Typical load per actuator > 50KG at max speed ( yeah yeah Dream on)
Main Structural elements = Open builds extrusion ( Cheap)
1605 Ballscrew & nut x 500mm long
Multiturn Pot for feedback control ( 2.5mm Toothed Pulley and belt system ref 3D printer parts )
12 - 24 Vdc motor Option
Driver = DC 2X32 DE Sabertooth or equivalent
Ardunio Loaded with SMC or Ians BFF Then Simtools once working design confirmed
To be modular ie
nema 23 or 34 Stepper Motor & Controller ( leadshine Nice but pricey)
if stepper motors can be used then mounting bracket changed to suit.
Cheapish CNC type Stepper motor drive (Pulse, Direction Enable)
Big issue ref stepper motor option

More info to follow now sorting out limit switches and feedback Pot mounting plate .. Cheers Guys

I have made 2 options ref the Actuator shaft , 1st one is a 20mm Carbon fiber Rod 20 Outside diameter 18mm Inside Diameter x 500 Long ..

the second option is a steel tube I got from of IKEA LOL 24mm Outside diameter Mild steel ..

Hope to have this running by Tuesdays as I need to tweak some bits but overall it should be Moving in anger very soon ( er how long it will last now that's another story )

with the above its my way of pre-empting the carbon rod failure if it happens and having something in its place .. as I mentioned " Trial and error" not very scientific but works for me cheers Guys

Keep us posted!

and please give us the total price if possible

wow..very interesting project.....what actuator model you used for this project?

Hi guys mad day at work so could not make the parts for feedback mechanisn, did not get the cad models revised either , crazy day , so slight delay but rest assured I'll have an update soon.

I will generate a provisional parts breakdown and cost per actuator as soon as I have a tested and working unit, and I optimize the parts,

The aim is for mostly off the shelf items and anything else would be made using general diy tools with no fancy machining (ok yes I used my diy cnc router and would like to use 3d printer) but once I find out what works and what doesn't then I'll redesign stuff with diy tools in mind

hi guys quickie update managed to get some bits done today so another step closer to power up or blow up LOL .. Just attached 1st draft Cad sketches . which will be tweaked numerous times as the test build progresses so this ia just outline info , prices will come soon..

Feedback will be Via 10 Turn 10K Potentiometer driven by GT2.5 3d printer type drive belt . mounted on the side of the unit. you may be able to see the Pulleys without the belt fitted in the drawing ..

Would have liked to use my 180° Rotary Hall effect Sensors but to be honest having hard time getting my head around how to convert 380 mm linear movement to 180° total sensor range .... looked at gears and they would be enormous LOL. to get the 2:1 ration , so initial tests will be via the multi turn Pots ..

Would be even better to make use of my 600 PPR Optical encoder but would mean using the Kangaroo and even though the replacements have turned up today I'll hang on before going down that road ..more info later -

Its looking great!!!
You coult save money by replacing the belt for a string and turn it a fuw times arround a disk upon the pot.
just my two cents.
regards Ad

Hi @adgun great minds LOL.. I did consider the string option and also using Tensioner attached to the Pot . something like this http://www.ebay.co.uk/itm/371569688510?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT .. again ebay is your friend so im waiting for a few to play with . Cheers for the tip anyways , all good info and never wasted

this is the idea I saw ref diy string pot using badge tensioner
or coverted tape measure

I have tried all of these and more and for a ball screw actuator could only recommend for simplicity and cost the tooth wheel and belt. The issue is that these actuators with small movements can move so fast that they can basically oscillate, with the spring or string either not tracking properly, or it just slips. My 2 cents worth.

Hi @SeatTime , mate your two cents worth is worth a lot more to us followers so feel free to throw in more money information LOL , my timing belt and pulleys turned up today , so you know I was gonna ask what gearing you opted for on your design ? cheers . my maths may be off but I figured max 400 mm travel ( more like 370mm though) using the GT2 Belt and a 40 tooth gear should see me get the 10:1 ratio for max pot travel ,,, looked all over your photos LOL and ill be dammed if I can see where you hid the Feedback pot off to man cave so hope to have some more pictures for later post

Few bits done thanks to 3d printer , idler pulleys designed and made so just did a quick mock up to check if it still fits after tweaking the belt shown is my GT5 type turns out I should have ordered a longer G2 , but the idea seems sound , so pot and limit switch mounting tomorrow and that means another step closer to power up time

More printed parts Gotta say this damm 3D printing system thing is infectious and now your always tweaking parts because the machine make it possible ,

My 1st idler pulleys were great but noticed that the topmost flange had taper ( trying to print an overhang in mid air is asking a lot ) anyways decided to make the pulley in two interlocking section with bearing sandwiched in the middle ,,,WOW what can I say the printer did such a good job I now have the working concept done and dusted and assembled ...

also made adjustable Micro-switch mounting plate with the option that the switch can be snapped in place or 2 x small screws as belt and braces option .... im def loving this 3D printing lark ..

Sorry about the loads of picture , when I figure out how to put then into one multi panel picture that should make this easier.. Cheers Guys

Hi Guys another wee update , Well I have only one more switch mount to 3D print and that will be all the mechanical elements in place , Phew

Could not resist so manually connected the motor to a 12 V battery just to check the leadscrew / Coupler /Motor alignment , ..Looks like that box is ticked , as everything seemed to run smoothly and without any misalignment related wobbles ,

Revise the Feedback pot fitting to a simpler option ( meaning my belt was not long enough so I improvised LOL ) .

Limit switch on fitted so just waiting for the other to come off the printer , then its the soldering ,and connecting to SMC utility for initial testing.. ( Bum Squeezing time , if you'll excuse the expression)

Ok he's back like a bad penny , with more updates , Good news all connected up and everything so far seems ok , I was hoping to use SMC3 for testing but need to do more reading as im using the 2x32 sabertooth controllers . being mr impatient I decided to connect up my other controller just to check the feedback pot control and limit switch operation in the event I did a "Calvin"

Ok test setup so far AMCUSB128 Controller driving my DE 2x32 Motor controller feedback by 180Degree Hall sensor with 2 Micro Limit switches as fail safe drive signal cut if she goes loopy ( that would be the Calvin Thing ) Motor supply 15V PSU but only 2Amp Max Current limited ( Safe testing option )

The initial trial with the above was to verify the control system works and feedback is good ( ultra sensitive with the hall sensor operated by hand )---Note shakey hands don't help LOL ) and with the Limit switches wired in parallel so either one triping will kill the signal to the motor controller ( I HOPE )

Next phase will be finding some screened cable for the 10 Turn 10 K Pot and then recheck wiring before testing begins in earnest..

@RufusDufus have a favour to ask ..beg beg , I saw a thread where you re-jigged the SMC3 Code ( mode3 ) for Sabertooths but was unsure if this was now a working code or held up for some reason , I'd really like to use your code as means to test this actuator ,
because of its flexibility , could you advise as to the latest state of play with that update ? Will I be able to use it as is ?

have to wait till tomorrow to print the thread as I find it easier than reading & scrolling down big threads .

Looking forward to see how this goes as I'm entertaining the thought of building something like this.

Why do you need SMC3 code if you have a AMC128USB?

good luck bro.. if you done your project, can u attach the design or something else to help me to finish my project..
thank you..