[juzwuz]

I came across two new Harmonic Drive HDF-040-128 gear sets at a salvage store and I bought them because they looked pretty cool but I don't really have an idea on what to do with them. They have a ratio of 1:120 I think. Can I just put a big 5 or 6 inch lathe chuck on it and drive it with a big stepper motor for a 4th axis? Anybody ever make a 4th axis with a harmonic gear set like this? Does anybody know how much this would cost new? Thanks!

[walter]

This seems to be light duty series, one web site shows similar item HDUC size 40 at $640. You have a component set. Housed unit size 40 can be $1000 each.

Harmonic Drive has zero backlash- works great for rotary axis. You`ll probably need a housing with some support bearing on output side. Input side can be mounted directly to motor.

This thread has some pics and 4th axis discussion--> http://www.cnczone.com/forums/showth...3&page=4&pp=15

[juzwuz]

Thanks Walter! Could you tell me what website you looked at with pricing information? I noticed in the thread about 5-axis machines that you bought some harmonic drives and you were going to design a housing. Do you have any design drawings or ideas on paper that you can share with me? Although, I'm still working on a 3-axis router so I'm not ready to tackle a 4th axis yet. Is anybody interested in a trade for one of these component sets? I'm interested in obtaining 3 gecko drives (for stepper motors). If there is no interest I'll probably just put it in the classifieds or on ebay.

[walter]

Sticky situation with the housing-I don`t have any design yet. Recommended tolerances for HD assembly are in 0.02-0.06mm range I think. Not an easy task. How are you gonna support the output side? Input side (wave generator) goes onto the motor shaft. HD housings seem to be using cross roller bearing.

Pricing comes from Canada ( US$). Look at electromate.com

[juzwuz]

I managed to scrounge up some housed harmonic drives from some robot parts. Two of them are 1:50 ratio and one is 1:100 ratio. The 1:50 ratio drives have a max torque of 55kg-cm (212 oz-in ??). The stepper motor is a Vexta 5phase 0.36deg/step with an encoder. I think I'll have to take the Vexta off and put on a regular 2phase stepper motor since I don't have a 5phase controller. I saw some 5phase drives on ebay but I wasn't sure how they work. Does anybody use 5 phase steppers? Can you connect the 5phase driver to the parallel port on a pc and use step/dir commands? What kind of 5 phase driver do you use?

I was planning on attaching a small 3inch lathe chuck to the harmonic drive and use this setup as a small rotary 4th axis. Will this work?

Thanks!

[walter]

Nice find. You can always go to manufacturer site and check out the drawings & specs for the device but it looks like all you need is a small lightweight chuck. :cheers:

Don`t know about the motor but since it`s nema 23 standard, you can easily replace it.

[juzwuz]

Normally I'm OK in taking things apart but this housed harmonic drive has got me stumped. I took the 4 cap screws off, that attach the motor to the harmonic drive, and it didn't budge. Then I started thinking how is the motor shaft attached to the drive? Any ideas? I don't want to use too much force in taking the stepper motor off. I guess I have to do some searching on the net to see if there is a schematic on how it's put together.

[walter]

Typicaly Wave Generator should just slide out with the motor --> http://www.hds.co.jp/HDS_hp_english/.../hd/index.html

The Wave Generator is usually attached via keyed shaft I think. Some gearheads use adapter flange and clamp-style shaft coupling. Better check numbers& symbols on the device, this looks more like a gearhead.

[CJL5585]

Normally I'm OK in taking things apart but this housed harmonic drive has got me stumped. I took the 4 cap screws off, that attach the motor to the harmonic drive, and it didn't budge. Then I started thinking how is the motor shaft attached to the drive? Any ideas? I don't want to use too much force in taking the stepper motor off. I guess I have to do some searching on the net to see if there is a schematic on how it's put together.

I have a unit that is almost identical, except mine has a servo with encoder. The unit has one shaft inside the other with a drift pin going thru both shafts. Also, I cannot get mine apart to drive the drift pin out.

Jerry

[juzwuz]

Walter....I finally got the motor off. Like you said, the wave generator slid out with the motor. :cheers:

The trick was to hold the housing and twist the stepper motor a bit and pull them apart. There's some heavy grease in there. Of course they came apart kinda suddenly and I put a small dent in the wood frame of a door :frown:

....with my wife watching

I'll get some pictures later tonight.

Justin

[2muchstuff]

Pictures? Of the door or of your wifes expression after you've hit the door.

[juzwuz]

Luckily the dent wasn't too bad, plus it was in the den which is pretty full of computer parts, cnc bits, and rc airplane parts. My wife probably wouldn't even go into the den except it has the diaper change table and the computer. She pretty much ignores everything in there except the little path to the computer.

Here's some pictures of the harmonic drive housing. There's some part numbers in there (14-50) which probably means size 14 with a 1:50 ratio? I'll take the 1:100 ratio housing apart to see what numbers are in there.

[walter]

Good stuff. This thing should have zero backlash- it`ll make great 4th axis.

[juzwuz]

I just bought a 3" 3 jaw lathe chuck and now I guess the trick will be to make an adapter plate to attach the chuck to the harmonic drive output shaft. I have a small drill press, aluminum plate and delrin sheets to make an adapter plate. Do you think delrin would be tough enough or should I just go ahead and make the adapter out of aluminum. I'm kinda worried about drilling the holes in the correct locations. Anybody have any tips on the accurate drilling of holes?

It's kinda funny that I'm working on a 4th axis when I don't even have axes one through three done. I also currently have too many harmonic drive sets now. I've put one of the HDF-040-128 (size 40, 128:1 ratio) in the classifieds/misc section if anyone is interested.

http://www.harmonic-drive.com/produc...onents/hdf.htm