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[JohnRobHolmes]

Some progress! I've had people bugging me for light weight motors for a long while, and never had the time or resources to get it done proper. As a first stop for quick and cheap modifications, I pulled out old CAD files I made for modding 540s. Here are two simple ones without heatsinking, I have some "cool" designs done too.


Mod 1, face the motor. Good for easy 5 or 6 grams without reducing motor efficiency and torque. Mod 2, thin the can radius. This particular path takes about 18 grams from the motor. The magnets lose about 10% flux on the work side, and lose 8% flux out the back side. People running very small (500mah) packs will have to bump up to the next biggest size. Reduce your motor weight so you can add it back on a higher battery pack? Some people want it, so I'll provide. Its good fun while I get ready for the next project anyway.

Doing a full tilt weight savings we can hit 36 grams removed before touching the rotor. Going from a TorqueMaster to a Crawlmaster arm loses another 8 grams,, and further lightening is possible. Not my cup of tea for motor design, but when I have the ANSWER on the perfect motor I won't be selling toy motors Hopefully that day never comes and I can keep learning until I'm pushing up daisies.


Next up is a router attachment and a fogbuster cooling system. I overheated a very expensive bit yesterday when I took the vac system off for a few minutes. It was doing a lot of cooling evidently! I also found an old router (its like a super sized dremel) that will give me 20k and 30k spindle speeds, and shall mount up to the head nicely. Great for PCB work!



I'll end with some quotes that help me keep the thirst for knowledge. Motor design and power electronics really mesh well with these ideals.

“Every person that you meet knows something you don't; learn from them.”
― H. Jackson Brown Jr.

“We are all apprentices in a craft where no one ever becomes a master.”
― Ernest Hemingway

“Be careful not to mistake insecurity and inadequacy for humility! Humility has nothing to do with the insecure and inadequate! Just like arrogance has nothing to do with greatness!”
― C. JoyBell C.





On to the next, we are done with this project. Pardon the dirty motors, these are just practice.

[chicklet]

I look forward to seeing all the new stuff you've been brewing (at Nats).

[rockhugger]

This is a fun thread to watch, thanks JRH

I particularly like the 3rd quote.

[JohnRobHolmes]

Chicklet- I've got plenty of time to build some swank motors to show off at nats, at least it feels that way! Just ordered a bunch of billet to start with. Magnets for the next project are due in any time now, and some really special armatures will be here about the end of the month. With any luck I can finish up at least one of three big projects I've had designed for years at this point.


rockhugger, thanks! I like the last quote too. Although I keep a full time job supplying the crawling community with electronics, I always have to step back and remember I am a small fish in a small pond. If I was really something special I would be working for aerospace or own a multi-billion dollar company. I do have electronics in government and private sector robotics, so maybe one day I'll earn the right to pound my chest, lol!

[jeepsohigh]

Nice to see the progress John. I can't wait to get them in my truck!!!

[JohnRobHolmes]

I'll be spending a few hours on the machine this weekend knocking out cans for the people that have shown interest in them. So far we have about 30 to make in varying degrees of lightness depending on the user's setup and needs. Shoot an email through my website if you are interested and haven't gotten ahold of me, prices are very nice for worked over motors


Just picked up a fogbuster. Coolant Sprayers I was going to build my own coolant system, but for the price I really couldn't turn it down. It was about $150 in parts to build my own, plus a lot of time and labor. This will be ready to bolt on and go! Once I get the coolant system on the machine I can let it run with a bit less attention. For now I'll just keep the vac on it with some occasional oiling. The vac is super loud, I will be ready to toss it out the window by the time the fogbuster comes in

The goal is to run this puppy 20 hours a week or more for the next year, then see if a bigger machine could be useful. I already have 16 hours scheduled for this weeks work and sales, plus prototyping and tool making on top of it. I have some PCB work to do as well, thats another few hours. I think it is a good start to a new machine! I'm pretty sure I will bring this into my workshop after nats so I can put my youngest grunt on it when he isn't doing armature work. It would be a great way to let me do more programming while the machine is running and teach him the basics of machining. If we keep it running steady for a year, time to look at getting something bigger to increase productivity.


Very glad I picked this up. I should have gotten this instead of the spoke machine a few years back !! Although the spoke machine stays busy too, so I guess I can't complain.

[BigSki]

I'll apologize in advance if this is really silly question, but do the motor cans have to be made out of steel?

[Hittman]

Nice! I cannot wait for these lw motors

[JohnRobHolmes]

Originally Posted by BigSki

I'll apologize in advance if this is really silly question, but do the motor cans have to be made out of steel?

Any magnetically iron alloy will suffice, plain steel is very effective and cheap. Back iron can only be forgon with a hallbach array, but the added weight, cost, and complexity of it makes "back iron" a hands down winner for power to weight with two pole motors. The magnet poles have to be coupled together to complete the magnetic circuit. It is the second half of the motor circuit that works in harmony with the copper coils and electricity. The motor will run without the back iron, but it becomes a more effective space heater and not so effective at rotary work. What is very interesting to me is how the motor design can be changed to use this more efficiently. If the distance of coupling is reduced, the iron can be thinner for the same flux density. I'm still a few years off on doing work in this direction, but maybe my Taig can help there. I have the designs made, I just need the skills to pull it off.


In an emergency pinch, a flux ring can be thrown on the back iron to get some "motor" back. For people running more aggressive back iron thinning (gonna be stage 4 or 5) I will provide them for tuning.




After work today I cleaned the mill area and planned out the weekends work. I'll try to limit my machine time to 4 hours so I have a restful weekend. I'm ancy though, I just wrote a multipart program and want to push some bits.




I gotta say my wife is being very supportive about this, I've been using a lot of early morning and late night time on this machine. The deal is I gotta scale back to 50 or 60 hours a week of workday after nationals.

[BigSki]

Thanks for the in-depth explanation about how the motor can works, I didn't realize it was an active part of the circuit, I thought maybe is was used as an relatively inexpensive manufacturing process as opposed to a cast resin/thermoplastic or injection molded part.

[JohnRobHolmes]

No problem! Even inrunner brushless motors have "back iron" in the form of a steel shaft or steel support structure on 4 pole + rotors.


Got some more work done last night and this morning. Evidently my weight estimates on basic lightening was off, in the good direction We are offering 5 levels of lightening kits on our Team motors and PRo Custom, and I am pretty sure I can hit 40 grams now on a level 5 . I have uploaded the features to my Pro Custom motors now Holmes Hobbies / Holmes Bikes :: Motors :: Brushed :: Holmes Pro Custom 540 and the prices are listed, and very affordable.


Built up a set of Team Crawl motors for a driver last night and came in just under 5 ounces with a standup endbell. Checkpoint is even lighter. I'm gonna cut some more parts for a while and post some pics later this weekend.



Billet for the 500 Puller should be here in a few days. I'll start doing work on the TTC Puller, 540 Puller, and XXXXXX Puller asap. More motor lines I have been sitting on for years at this point, its been frustrating! I will need to make assembly tooling for them all, and now I have ZERO excuses.

[eric113]

Dang John! Wish I lived closer, Or you need move to Austin. I could use a part time job.

I will be in your neck of the woods next weekend though.

[JohnRobHolmes]

Oh yeah, how close you swinging by?


500 Puller screenshots. May or may not have heatsinking on the production versions. I also have CAD files made to upsize this for 540 motors, although I don't think it will be any lighter than a milled out Sagami can.

[JohnRobHolmes]

A little fooling around this weekend with fiberglass. Some timing rings to keep weight weenies happy. Copper stuff is just sheet I had laying around for some express built motors, blue stuff is G10 grade. I have a few more sheets of blue G10 and carbon fiber coming this week to pop out enough for the store. The blue or black g10 endbell kit should retail at $10 including alloy spring perches and full alloy hardware. Carbon fiber kits should be around $15. Comes in at 7.4 grams less than regular hardware. Once my order from Sagami comes in with some custom parts we will reweigh the kits, it should be even a bit lighter than what we are using now. With these parts plus some additional work I have dropped 9 grams off the endbell alone for motors going out this week to some lucky fellows

[BigSki]

I have another motor question if you have the time. My mind was thinking out loud while running some scalers yesterday and the idea of an on-board generator system for re-charging the LiPos came to mind. Question- how much wattage would a, say for example, 35T 540 motor put out if it was used as a generator instead of a motor?

[JohnRobHolmes]

maybe 90 watts if you had active cooling. You using a little gas engine to generate from? If it is for practicality you might as well just carry an extra pack. If it is just for giggles and grins then go for it!



Forgot the good parts of cutting the fiberglass. Used an 1/8" carbide bur at 10k spindle speed feeding right at 350ipm. Worked a treat! Ideally I want 20k or 30k spindle with a bur, so I'm still going to make a router attachment for the mill.

[Devil Inc]

Keep the goodies coming, I like seeing pictures of products

[rlockwood]

350 ipm on the taig? is that a typo..? thats ~7000rpm at the stepper.. i'm guessing 35ipm?

[JohnRobHolmes]

Yeah, 35.0 ipm. 350 would be fast for steppers! On 1/16" the motors take 50ipm just fine, on 1/8" 30 or 35 is as fast as I can push with a bur before the motors start losing steps.

[BigSki]

Originally Posted by JohnRobHolmes

maybe 90 watts if you had active cooling. You using a little gas engine to generate from? If it is for practicality you might as well just carry an extra pack. If it is just for giggles and grins then go for it!

More of a giggles and grins, thinking out loud for right now. The initial "concept" was a dual motor setup, only one of the motors would be the generator. I agree 100%, it's more practical to carry extra batteries!