[stevenmotor]

Hi,
These are my stepper motor for you reference.Welcome to discuss with me [email protected]


Steven

[dertsap]

brillient !!!!
nice to see a guy having fun !

[RotarySMP]

Nice work. Does that harmonic drive have any backlash?

[BobWarfield]

Sorry to be late answering this last question. One advantage of harmonic drives is they have almost no backlash. There's quite a lot written about them on the Internet if you google. They come up pretty often on eBay fairly cheaply. Widgit's 4th axis is a nice compact design because of the harmonic drive.

Best,

BW

[wizard]

Hi WidgetMaster;

Thanks for the inspiration. I'm a working stiff at the moment and often take inspiration from your posts even if finding the time to work on some projects is a bit stressed.

I will keep this thread in mind (hopefullly as I'm past 40) when out and about looking for deals for parts and such.

The only thing I see missing is the ability to clamp the fixture plate to the housing. Was this avoided for a reason or do you think it is a bad idea overall?



Dave

[leberen]

Simply amazing,

the scale of your a axis (4th) is amazing, very nice work for that HUGE motor. My Maxnc 4th axis is 50% complete, your instructions have shown me that it can become complete soon! Thankyou for your writeup.

[fyffe555]

Nice work Widgetmaster.. an appropriate name there..

Is there a bearing between the harmonic drive and the work holder or is the drive bearing holding all together?

Also would you think an iron angle plate would work as the basis fo rthe support base?

nice job..

[widgitmaster]

Nice work Widgetmaster.. an appropriate name there..

Is there a bearing between the harmonic drive and the work holder or is the drive bearing holding all together?

Also would you think an iron angle plate would work as the basis fo rthe support base?

nice job..

Thanks!

This particular Harmonic Drive had a massive hub on the end, so I used it to support the faceplate!

An iron angle will work, its just easier to make things out of aluminum! Steel is tough and wears out my cutters!!

Thanks again
Eric

[juzwuz]

Hi! It's been almost a year but I finally installed the harmonic drive 4th axis that Widitmaster made. It fits perfectly on the tooling plate that I got off of ebay. I still have to figure out how to connect up the 5-phase stepper motor with the 5-phase driver. I guess I could always just replace the stepper motor with a regular one. Then I'll have to figure out what to make with the 4th axis and how to generate the g-code.

[BrendaEM]

It's just a thought, but...

As someone who doesn't have enough hands-on experience, it would be interesting to know if there is any measurable taper to the "L" sides. The outside edges should be dead square, but I wonder if the inside might be a bit tapered caused by bit deflection, or the large bit you used was strong enough not to deflect in a measurable way.

If you wanted an additional bit of angular accuracy, could you not take one minute fly cutter pass on the inside of the "L" bracket, only where the motor flange makes contact? It wouldn't be without risk, because the fly cutter might want to whack or nick the nice radius you made, so the fly cutter would need to be tested to see if it swings into anything.

It looks good, congratulation.

[Stepper Monkey]

I guess I could always just replace the stepper motor with a regular one.

I would strongly recommend against that as it will probably destroy the unit instantly. There are gearheads that are built as separate units from the motor, but as far as I know, from what the factory rep has told me anyway, that the 5-phase steppers are built onto them as a unit and because of the way they are assembled attempting to separate them can ruin them instantly or at best throw off the alignment, which is EXTREMELY critical. People apparently send units back to the factory asking for for re-alignment, but it is usually cheaper to just buy new units if that has happened - so they can be trashed real fast pulling them apart.

[Atomic_Sheep]

Seems like making it properly also means it's going to cost a fair amount. In fact it looks like the Chinese 4th axis knock off are going for a similar price to just the Harmonic gear itself in this build.

The question is, would it be worth spending a bit extra and getting everything done properly or is the Chinese unit good enough? This is obviously in the metal section so perhaps the Chinese isn't even in the same league as this home brew but just wondering about others' opinions.

I think for me at the moment, I can probably get away with just working with aluminium at the most so I don't need a fully fledged metalworking monster.

[D.L]

Don't change the motor, I understand the 5 wire to be the same as 6 wire with a shared centre tap for two of the inputs.
It should be reconfigurable to use it as 4 wire, just as a 6 wire can be used as a 4 wire by ignoring 2 of the inputs which removes the centre taps and connects the coils in series.
Surely this has been discussed elsewhere in the past 20 years in cnczone?

[CL_MotoTech]

First off, this thread is more than a decade old. So why resurrect this sucker and not start a new one?

Second off, you get what you pay for. There are genuine Harmonic Drive servo mount gear heads (planetary drives not harmonic) that have less than 3 arc minutes of backlash are available used on eBay for less than $200. I bought one and it's like new, not a mark on it. and I paid $195 shipped. 3 arc minutes at a 4 inch radius represents around .0035" of backlash. Maybe I got lucky with my unit (i've only ever owned one so I don't know) but I can only measure around .0015" of backlash at 4" radius, which is around 1.5 arc minutes. That's less backlash than both my X and Z axis, which both have around .002". So if I am to complain about backlash I would probably start there first.

The HD gearhead is 33:1 ratio and good for 70 nm of torque. The stepper I am using is good for around 6nm at 6amps. I am running it lower than that though, only 3.5 amps. Given this, it would require around 150lbs of force to turn the axis at the maximum 4 inch radius and more than that the closer to the axial center. Once I max out the amperage that number will increase significantly.

GIven all of that, I built a trunnion table (18" bed) using the parts outlined above as well as a host of other materials and bits for around $550. Yes there was machine time that I'm not counting, but it's a far superior table (or will be once's it's all squared up) than any of the Chinese units

[asuratman]

Do you guys know or have some experiences where to buy Chinese's harmonic drive ? Maybe a lot cheaper. Which product do you recommend? I saw on ebay there are lot of HD model or type.

[asuratman]

I found the one like on the link below, I did not see the one like yours, easy to install.

https://www.aliexpress.com/store/gro...4b24ae2bXNuUof