Hoddem's DIY Linear Actuator

yup tried without sabertooth. also bypassed the arduino and used hardware serial. I ordered a simple rs232 but we will see. I think its messed up. Ive never had any issue like this. it wont even detect it. the serial connection is working as I can send signals just the kang is dead. I even tried to connect it with a working ch340(pulled from momonster for wind setup) no joy. I'm pretty sure this one is junk but we will see what DE has to say. hoping im missing something small. I do that often lol.

havent tried to connect the sabertooth by itself only kang+sabertooth and kang by itself. I'll try the sabertooth alone.

Love the video. Looks like that motion would be perfect for a 2 dof.

Im in the process of collecting the parts to build 2 actuators.

It will be interesting how they compere to scn5's

Hoddem - what is the latest on your sim ?

I kind of dropped of the face of the earth didn't I. life got busy, added another kid, moved into a different house etc. etc.

I was just going through my stuff and had the actuator out again, it kind of got my gears turning. I don't have any plans right now, but this is definitely an unfinished project that I need to get back to.

I think deep down I know that I will eventually build a 6DOF, but right now this is just a science experiment/engineering challenge.

Agree, it takes quite a commitment of time and resources to go from one to six actuators. Often hard to find both when you are bringing up a young family.

Hi Hoddem,

A family takes up a lot of time and is what is really important in life, but a sim build is good to escape to once on a while !

Can you clarify the faster actuator is because the ampflow motors run at a higher rpm

Did you get to try the 1610 ballscrew ?

Do you think a 1kw 3000 rpm motor would have enough grunt for a 1610 pitch ?

Happy new year !

Hi Gadget
To keep it simple 1NM give 100kgf with a 1605 screw.
2NM give 100kgf with a 1610 screw
It will give more force, but there is resistance in actuator and this works allways!
With a little luck a 1KW motor will be enough for a 1616 screw
100kgf a actuator will be fine for a 6 dof
regards AD
sorry for the bad english

So basically everybody is using the 1605 profile becasue their motors are not that powerful ?

The rpm of the motor must be important as is the stall torque

A fast actuator that takes a while to get moving may not be suited to a sim

Most motors are 1NM rated torque or less.

Motor rpm gives speed. 3000rpm /60sec.\=50round sec X screwpitch= 250mm/sec with 1605 screw
1NM in stall gives 100kgf to, you must stay in there couninius area.

Accel. from a actuator is made in G
An 6 dof with 6 x100kgf actuators and a payload from 150kg .can accel with 3G in heave.

1G= gravity from 0 mtr sec til 10 mte sec in 1 second
Top speed actuator 250mm sec 10mtr/0,25mtr sec\=40
1/40\=0.025 sec to accel from 0 til 250mm sec with 1G

the motors i have in mind are 3.2 NM

Model: MY1020
Voltage: 48 Volt DC
Output: 1000 Watt
Rated speed:3000RPM
Rated current: 26.7A
Rated Torque: 3.2Nm

so this is approx 300 kg from a 1605 at 250 mm/sec

and 150 kg from 1610 at 500 mm/sec

is 250mm/sec approx 1G Accel ?
and 500 mm/sec approx 2G Accel ?

With 6X100kg force and 150kg payload you can,t accel. faster than 3G, it,s a mechanical law
1G is the time to accel. to topspeed this is 0.025 sec with 250mm topspeed and 0.05 sec with 500mm topspeed
accel. in 0.025 sec to 500mm topspeed will give 2G

It works in two steps.
Step one. working vertical
A 100kgf actuator with 100kg load will only hold, there is no force left to go up, going down goes wrong there is no force left for braking.
A 100kgf actuator with 50kg load will hold and there is one time the load on force left for accel. and braking. this gives 1G max.
A 100kgf actuator with 25kg load will hold and there is 3 times the load on force left for accel. and braking. this gives 3G max
Step two. You can calculate the time for it
hope this helps
regards Ad

So far with my new motor and a 1610 ball screw I was able to hit roughly 900mm/s with no load. That is a combination of the max rpm at nearly 6000 and the 10mm pitch ballscrew.

My motor has a peak of about 4.8nm, so it’s no slouch. I have yet to do any load testing though, so in practice I don’t know what’s going to happen.

wow thats impressive - is this the 800w Ampflow motor ?

This is the ampflow e30-400, it’s a really nice motor and they provide data so you know exactly what you are getting. They have even more powerful versions, but finding a motor controller that can take advantage of the higher power draw is not easy or cheap.

Here is the amazon listing.
AmpFlow E30-400 Brushed Electric Motor, 12V, 24V or 36 VDC, 5700 rpm

Notice in the description the motor has a stall torque of 11nm, however that is at nearly 280 amps. The max power for the Sabertooths 2x60 is 120 amps for short bursts.

This motor may be suitable for a direct drive wheel !

ampflow E30-400 and sabertooth 2x60 is what i went for... i just read your thread and i was very impressed by your work. i hope i can achieve what you did.. i have to look at the encoder situation, i like how u implemented it

may i ask what kind of plum coupler did you use? is it a D30 L35?

This is the exact coupler I purchased
https://www.ebay.com/itm/BF-10mm-x-...m1c2c441640:g:8~wAAMXQMXRQ56yV&frcectupt=true

I had been using a smaller version I think 25mm diameter and 30mm long and it was too small for comfort

i ended ordering a D40 L55.. what type and size coupler do you use now?

Hey guys,
I have had this burning in the back of my mind for a few months now and I think I have come up with a compromise that will keep me moving towards a full motion rig. Initially I was going to just pull the trigger on the full 6dof system and start buying parts, but I pulled back a bit mostly because of the complexity of a full 6dof system. I would essentially be scrapping almost all of my existing system and starting over. After lurking around on the forums here and there I came across the SFX-100 thread.. I really like the simple design, but I don't like being locked into 240v servos (no easy access to 240v in the new garage). So my new game plan is to build a set of SFX style actuators utilizing the Ampflow E30-400 motor and Sabertooth/Kangaroo control system. I will slightly modify my existing rig to accommodate and hopefully for a relatively low expense and not a lot of work I can have a 3dof system up and running with as much success as the guys running the SFX-100's seem to have had. I have already finished the preliminary design and ordered all of the parts needed to build the initial test actuator. Luckily most of the parts on my actuator will transfer to these so if some day I decide to go 6dof I could still do so with less cost then starting from scratch.

Specs
ampflow E30-400 Motor
Stall torque -4.6nm
Max RPM @24V 5700
1605 Ballscrew
Max speed - 475mm/s

According to @adgun, 1nm stall torque gives 100kgf of lift with a 1605 ball screw. I haven't run the calculations but if that is correct I will have 1840kg of lift with 4 actuators. These numbers start to get a little scary thinking about doing a 6dof with 6 actuators and 1610 ball-screws. 4.6nm*50kg*6 actuators = 1380 kgf /200kg rig = 6.9 g's. these numbers seem high, but again I haven't done any actual calculations.

So here is the preliminary design




As I wait for the first shipment of parts to come in I will be adjusting my cad model of my rig to accept the new actuators.