Carbon Fiber Harmonic Drive (Strain Wave) Telescope Mount
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- čas přidán 26. 06. 2024
- The telescope I built in my last video was amazing, but the mount wasn't. So I built a better one!
Download Free Project Files - designbydave.net/telescope-mo...
OnStep - onstep.groups.io/g/main/wiki/...
Alan Zhao's Mount - alanz.info/posts/2022/07/diy-...
#3dprinting #davebuildstuff #designbydave #harmonic #strainwave #telescope #astronomy #astrophotography - Zábava
Download Project files - designbydave.net/telescope-mount/
Watching this while drinking a beer this whole time thinking to myself, "man those layer lines on those prints are gonna snap under all that weight."
Haha. perhaps I needed a few beers during the design phase to expect that was coming. A bit of additional info though that I didn't mention in the video is that I am pretty sure now that it perhaps wasn't just the weight of the telescope that caused the parts to fail, but an assembly error. Hard to describe, but I'm pretty sure during the assemble I "preloaded" those parts with the mounting screws basically acting like a jack, splitting the layers. So, it's possible that with correct assembly that the parts would not have failed. At least, not right away. But I'm glad it turned out that way because the re-designed parts are significantly stronger and I have full confidence in the mount handling the intended payload.
@@designbydave yeah that's true. I haven't tried that particular filament but it looks strong for what it is. Will have to give it a try. Just found your channel and you have some really interesting projects!
I don't have objective data myself, but other's experience / data shows that Polycarbonate has some of the strongest layer adhesion of any of the common FDM materials. That layer adhesion has also been shown to improve with an enclosure and gets stronger the warmer it is inside. It's my favorite material by far to print structural parts. @@viniguez487
Great video, 1st class workmanship 👏👏👏
Thank you very much! It's taken quite a bit of trial and error and tweaking but I'm really happy with how the mount is performing now.
thanks for helping tarantula friend :)
Haha, yeah He didn't need my help it turned out. They are very cool creatures!
Dude this is awesome. Wish i had some of the equipment available to build a mount like this
Yeah, having access to even a basic mill and lathe opens up a lot of possibilities
Great build! I am planing to make my own eq mount but 3d printed. Clear skies!
Thanks! Awesome go for it. There are a lot of (mostly) 3D printed designs out there. Search Printables.
Hi David, cool project man. where do you buy those carbon fiber tubes that have there. Thank you
Thanks for checking it out. Those tubes were scrap from a former job. I usually source carbon tubes on eBay. Not sure you can find the exact size, but maybe something close and then modify the design to use.
Have you pondered making an equatorial wedge for it? Just an idea. Can't wait for my parts to come in...lol
I have thought about that yeah. Since this was primarily intended for visual use, an equatorial wedge was a low priority. It is something that I would like to visit though someday in the future.
Awesome!!! I’ve been wanting an Equatorial mount for awhile now and there so expensive. This is awesome that people are starting to build their own. Do you by chance know if you can control the mount with a ZWO Asiair plus? Thanks for the amazing vid!!!!!
Thanks!
This mount is controlled via OnStep, open source telescope control software. I know it can be connected to a PC, tablet or phone via a generic ASCOM driver. So, I suppose as long as the Asiair can control a generic telescope device like that, then it should be good.
Absolutely incredible. Really helpful for me as im looking to make something similar. How do you source the harmonic drives? How expensive can they be? Is there any harm in buying them used?
Thanks, glad you found this helpful. Check the link to my website in the description. There is a bill of materials with links to source the Harmonic drives. I brought mine used on eBay but later found a source for a Chinese version on Aliexpress that is almost half the price new. Should be perfectly fine for this application.
Thanks a bunch! I found the excel file and that price is truly unbelievable. A few questions though? Are the stepper motors listed in the file the updated ones you state? Also, how is manual movement in the mount? How stiff/smooth is it?@@designbydave
Yes, the steppers I changed to are the 5:1 ratio steppers that are listed in the BoM (actual reduction is 5.18:1, see specs.) This gives 518:1 total reduction, which at 32 microsteps gives 9208.9 steps per degree. I'm finding the tracking performance to be excellent for visual, but not sure about long exposure imaging.
There is no manual movement of the mount unfortunately. It is not possibly to "back-drive" such a high reduction ratio and push the scope around by hand. The only way to achieve this would be some form of clutch mechanism. I've tried to figure out a simple way to accomplish that but haven't gotten anywhere. Not having manual, push-to, movement is kind of a bummer, but I've been able to get OnStep running consistent and well enough that it's not been necessary. Having a clutch mechanism would be a great upgrade to a "v2" of this mount. @@rayyanimran1557
Mt. Pinos is a great spot but gets too crowded with a bunch of non-astrophotographers showing up late and leaving early. Have been going to another site just down the mountain called Chuchupate. There's a parking lot at the trail head with restrooms. Less packed and less people coming and going.
Cool, thanks for the info. Yes, that night there were a lot of people with car lights but that also meant there was a lot of people to share the views with which made it a lot of fun. I always get a kick out of showing people the views for the first time.
@@designbydave definitely great for outreach. Maybe I'll see you up there some new moon!
I just (mostly) finished my new 12.5 inch dob (check shorts, will make full video later) so I will definitely be looking to get out in a couple of weeks! @@viniguez487
Great craftmanship. Beautiful mount. How much were the strain wave units? I just would like to know what I'm getting into here, cost wise~!
Thanks!
They $235 each, but I've since found a Chinese supplier that has them for $140 each. Check the documents linked in the description.
Ok, thanks for the info. Did you farm out the machinging at all? If so, to whom did you work with? @@designbydave
@@microreniassance2929The two aluminum plates were laser cut ordered from sendcutsend.com
Thanks much for the information.@@designbydave
Darn it, I ordered the MaxESP3 instead of the MaxESP4. Hope it works. One week until my harmonic drives arrive. Need to purchase stepper motor drivers. Thinking of the TMC5160T. What stepper motor drivers did you use?
I think there isn't much different in performance but I'm not very well informed on the subject. I just ordered a complete OnStep board from Chad Gray, see bill of materials. Stepper drivers where included.
Hello, I was wondering if you could share where you bought the Harmonic Drives. I've seen them on eBay and AliExpress but none of the listings really give confidence lol. I've tried contacting companies directly with no luck.
I list two sources in the project files on my web site (Google Drive link) - designbydave.net/telescope-mount/
@@designbydave ahh. thank you for the quick response!
Dog gone it! My harmonic drives arrived unassembled with no instructions as to how to assemble them.
okay, I think I assembled them correctly...lol I'll share a pic if I get it running.
Dang, which ones did you order?
I should have it assembled by the end of this weekend and will share a pic. Waiting on stepper drivers. Built my board myself.@@designbydave
Hello again, I have three questions. Did you set the set screw into the flat surface of the stepper shaft or just to the shaft? Did you have Loctite 243 on the set screw? Did you use a 3 mm key in the harmonic drive keyway?
My Harmonic Drives have 2 set screws, so one is against the stepper motor output shaft flat spot, the other is about 90 degrees from that.
I used Loctite 242
I don't recall the hex key size
Are your 3D print files available as STL or OBJ files for those of us not having SolidWorks? Thank you.
I have step files available
I got it. I found a way to convert to STL using eDrawings Viewer.
Thank you for your patience and understanding. I did not know what a STEP file was. I now do. Opened it using FreeCAD.@@designbydave
I see you have reduced your stepper motor gear ratio. Will this not reduce the payload capacity of your mount? What is the weight of your fully configured telescope before you mount it? Thank you in advance.
Yes I suppose it might, but it's not been an issue for my. My payload is only about 6 pounds.
I am curious what payload your design can handle. Not worth risking breaking your 3-D printed parts though.
I'd be curious too! @@mr.harris8185
@@designbydave with the PG at 27:1 and the harmonic drive at 100:1, that's 2700:1 from the stepper motor... no wonder it was a bit slow. What is that - about 66 degrees per minute if the stepper motor is doing 500rpm? Going down to the 5.18:1 PG would give about 347 degrees per minute, almost 1rpm, would that be a better ratio? Would it be better, do you think to drop the PG ratio down to 5.18:1 like that or drop the harmonic drive ratio to 50:1 or 30:1 and maybe not drop the PG as much, say 50:1 and 14:1 respectively?
@@JeremyTaylorNZ I did swap to a 5:1 planetary gearbox and that not only improved the slew speed but they also run almost silent.
Please provide info on the harmonic drives - Cost, part number, where to order from. Thanks!
Check the link on my web site. It's documented in the bill of materials. designbydave.net/telescope-mount/
@@designbydave Got it, thanks. I missed the button for the link before. BTW, how is the Strain Wave mount working for you so far?
It's great! After a lot of tweaking, tuning, trial and error, I've got it to a point where it's very reliable. Quick, easy and fun to use. Exactly what I was looking for. @@MikeHammer1
@@designbydave Good enough for astrophotography? That is where my interest lie. Of course your telescope is a long focal length so the higher magnification will amplify any inaccuracies or shaking so it may be hard to determine suitability for my application.
I'm not sure if its good for imaging. I would need to build a wedge for it as I'm currently running it in Alt-Az mode. Maybe my next project... @@MikeHammer1