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Thread: VFD Capra...Can I Still Call It A Capra?

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Old 05-02-2020, 05:19 PM   #1
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Default VFD Capra...Can I Still Call It A Capra?

If you don't look too close it still looks like a Capra.
This has been an ongoing build since I got the Capra kit in December. It's had a number of changes over the last few months but, since picking up a 3d printer at the start of our State's lock down to stave off boredom, I've gotten a little carried away. I've never had a 3d printer before and it was so much fun designing things for the Capra and printing them out that it was a little hard to stop. This is the result. Laugh if you must. I know I have been.
Most of the big things are done except the sliders and the battery tray which is on hold until the VFD dig is back in stock so I know what I need for clearances. I'm sure there will be other things that change since I can't seem to leave well enough alone.

Edit: The title was meant to be an actual question. Since I'm fairly new to the forum I wasn't sure if it was appropriate to post my "Capra" in this group with how little of the actual Capra is left. Since the post didn't get moved I guess it's OK.
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Last edited by mjensen; 05-03-2020 at 08:24 PM. Reason: updated
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Old 05-02-2020, 05:40 PM   #2
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Default Re: Can I Still Call It A Capra?

That is an awesome project! How's it crawl with the VFD?

In the past, the categorization of a rig was determined by its axles. That would mean this is a Capra-based rig. But is it still a Capra? I'm not sure.
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Old 05-02-2020, 05:54 PM   #3
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Default Re: Can I Still Call It A Capra?

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That is an awesome project! How's it crawl with the VFD?

In the past, the categorization of a rig was determined by its axles. That would mean this is a Capra-based rig. But is it still a Capra? I'm not sure.

The front axle just got delivered this morning so the way you see it in the pictures is as far as I've gotten. I did manage to keep the wheelbase the same as stock and the link geometry close so with the motor further forward and lower, and the battery lower, the center of gravity ought to be lower and more front biased than stock. Whether it will crawl better remains to be seen. The Capra was designed by people that know their stuff...I'm just some old bored guy with an out of control 3d printer.
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Old 05-03-2020, 06:29 AM   #4
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Default Re: Can I Still Call It A Capra?

I like it!! I'd love to try it out. Where do you plan on placing the battery, and how small does it have to be, like 450mAh? One of the guys I crawl with uses those in his 10.2 lightweight chassis but it dies in about 20-30 minutes of crawling.
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Old 05-03-2020, 07:13 AM   #5
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I like it!! I'd love to try it out. Where do you plan on placing the battery, and how small does it have to be, like 450mAh? One of the guys I crawl with uses those in his 10.2 lightweight chassis but it dies in about 20-30 minutes of crawling.

The battery tray is going to sit on the flat rail area between the fuel cell and the transmission. I have a couple of 4300mAh 3s shorty packs that I got when I first ordered the Capra kit. I may try smaller batteries in the future if balance proves to be an issue but right now with the 4300 sitting where the tray will be the weight bias is about 55% front, 45% rear without anything added like brass.
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Old 05-08-2020, 11:32 AM   #6
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Default Re: VFD Capra...Can I Still Call It A Capra?

I haven't had a lot of time this week to work on the Capra but I did manage to draw up and print out some sliders for it. They don't fit perfectly and probably should be a mm or 2 wider but it should be an easy fix when I print up the final version. I also replaced that ugly front grill with the stock one since I've moved the hinge for the cage to the rear. With the sliders and original grill it looks like a Capra again.
There's still a lot left to do, battery tray, electronics, paint, etc. but the way the weather has been (they're predicting snow for tomorrow) so I doubt I'll be getting out anytime soon anyway.
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Old 05-13-2020, 11:03 PM   #7
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Default Re: VFD Capra...Can I Still Call It A Capra?

I haven't made any more progress on this build since I'm waiting for the VFD dig which is finally back in stock but I'm curious about what other folks' Capras weigh in at. Mine as it sits in the pictures I previously posted with a battery but no electronics weighs about 6 1/2 pounds. This seems heavy but having been out of the hobby for a while and coming from racing buggies I really have nothing to compare a crawler to. All the 3d printed parts are currently PLA which is heavy but once I know everything fits together as it should and link locations etc are OK they will be printed out in Carbon fiber/polycarbonate which is lighter and stronger so there will be a bit of weight saving there. Whether or not it will make a difference or if it's even something to be concerned about, I don't know. Opinions would be welcome.
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Old 05-14-2020, 06:56 AM   #8
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Default Re: VFD Capra...Can I Still Call It A Capra?

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Mine as it sits in the pictures I previously posted with a battery but no electronics weighs about 6 1/2 pounds. This seems heavy but having been out of the hobby for a while and coming from racing buggies I really have nothing to compare a crawler to.
Mine without a battery weighs 6 pounds 2.5 ounces. That's without a battery, but with brass portal covers at all 4 corners.
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Old 05-14-2020, 08:34 AM   #9
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Default Re: VFD Capra...Can I Still Call It A Capra?

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Mine without a battery weighs 6 pounds 2.5 ounces. That's without a battery, but with brass portal covers at all 4 corners.

Thanks. I guess I'm not too far off. The big battery packs I have weighs 8.9 ounces and I only have brass on the front. The electrics weigh about 4 ounces so all together I shouldn't be too far off what you are running at.
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Old 05-23-2020, 02:25 PM   #10
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Default Re: VFD Capra...Can I Still Call It A Capra?

More setbacks than progress this week. I did manage to get the links sorted and I got the VFD dig installed although I need to sort out the linkage from it to the servo. I ran into a problem with the battery tray since I needed to raise it a bit more than I intended to clear the dig linkage but I failed to consider how low the center console area of the interior was so the cage will no longer close. Never would have made it as an engineer as I don't think far enough ahead I guess. Anyway, some major rethinks are in order. Unfortunately I'm about out of printer filament and delivery times are anywhere from 7 to 10 days from Amazon so it might take a while. Our home confinement got extended until the middle of June so hopefully I'll have things figured out by then.
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Old 05-28-2020, 05:28 PM   #11
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Default Re: VFD Capra...Can I Still Call It A Capra?

I was able to give the Capra a bit of a test run today. Only in the house (since my yard currently looks like a cornfield of weeds as my mower needs some repairs and I spent the money I had set aside to fix it on Vanquish bling but who cares what the neighbors think) Anyway, aside from needing some gear adjustment to compensate for the stock VFD gears and the Capra axles, it did surprisingly well climbing carpeted stairs. I'm a bit disappointed in the Crawler Innovation foams I put in the Hyrax tires as they creep around inside the tires when there is a side load on them. Since they have such a good reputation I expect it might be an issue with the inexpensive China wheels I mounted them on. I'll probable swap them around with the other set of wheels and tires I have for the Capra and see if the fixes the issue. Even with the overly large battery pack the weight bias and center of gravity seems quite good but I've budgeted some smaller packs for next month so it should improve even more.
Sorry there are no pictures as I was excited to see the Capra under it's own power and didn't think of it. As far as videos go, I am a bit of a Luddite and only got a smart phone a short while ago so I haven't actually figured out how the video function works. Soon hopefully.

Last edited by mjensen; 05-28-2020 at 10:12 PM.
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Old 06-28-2020, 07:04 AM   #12
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Default Re: VFD Capra...Can I Still Call It A Capra?

I spent some time this month redesigning the chassis and battery tray. Using a smaller 1500MaH battery pack I was able to lower the tray about 8mm and still have clearance for the DIG. I also replaced the kit Capra front axle I was using for rear steering with a Supershafty aluminum housing. In the next few weeks I hope to get the final versions of all the parts printed out and get it finished.

Since the kit axle was the last major part from the kit that I had in the custom build I decided to put the kit together. I pulled all the electrics out of the other build since I had been considering going brushless anyway so now I have a complete Capra that I can compare the custom to. The paint didn't come out great but in 40 years of building RC cars I've always been a horrible painter so it wasn't unexpected. If all goes well I might even be able to get it out on the rocks this afternoon.
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Old 07-24-2020, 03:29 PM   #13
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Default Re: VFD Capra...Can I Still Call It A Capra?

It's been a bit since I updated this. I finally got around to finishing my redesigns and made the first prints in the carbon/polycarbonate filament. I still need to tune up my printer a bit more as the prints are a little rough but they are noticeably less flexy than the original Capra cage and the PLA I was using for the prototypes. Plus they don't have the heat issues PLA has.

In the redesigns I tried to triangulate the chassis better as well as simplifying the layout to make it easier to print. I relocated the DIG servo to the fuel cell and the electronics to either side of the transmission. The battery will sit in front of the fuel cell. I moved the front and rear upper links from the printed chassis to the VFD skid which required me to make new links. The link geometry is no longer the same as the stock Capra that I was trying to keep but it seems more solid now. Time will tell if it's going to work. The whole chassis sits about 8mm lower than the stock Capra when sitting on the stock skid. The motor sits about 12mm lower than stock and is much farther forward so even with the battery and DIG servo behind the transmission I think the CG will be lower and ahead of stock. I guess I'll find out when I get things put back together.

It's funny that this started out as a way to kill time while we were under lockdown and I hadn't really intended to spend a lot doing it. It didn't take long to get expensive especially since I've ended up building 2 cars instead of just modifying 1. I did compromise on the motor and ESP for this one. I wanted to go brushless but I ended up going with a Holmes Crawlmaster Pro and a Hobbywing 1080, pretty much what I have in the stock Capra.
Anyway, here's a few photos...
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Old 07-24-2020, 03:49 PM   #14
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Default Re: VFD Capra...Can I Still Call It A Capra?

Very cool project, nice work.

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Old 07-24-2020, 05:36 PM   #15
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Very cool project, nice work.

Sent from my SM-G970U using Tapatalk

Thanks. It's been a lot of fun and it's given me something to do during this virus thing which was really the only reason I started it. In the end it doesn't really matter if it's an improvement on the stock Capra and I have no expectations it will be but it does take care of the two small things that I didn't like about the Capra, the limited ability for gearing changes and that it's a pain to work on.
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Old 07-26-2020, 09:21 PM   #16
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Default Re: VFD Capra...Can I Still Call It A Capra?

A few more pictures with all the mechanical bits put back on.
The articulation of this chassis is slightly less than the stock Capra which was expected since it has 90mm shocks rather than the stock 97mm.

I did end up with plenty of clearance for the DIG linkage which was a concern after moving the servo behind the transmission. The only short servo horn I had is plastic so I'll have to find a metal one at some point.
The stance seems OK with the overall height of the body lower than stock while still having more clearance under the skid and fairly flat lower links.
Now I just need to figure out where to put all the electronics.
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Old 07-31-2020, 01:16 AM   #17
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Default Re: VFD Capra...Can I Still Call It A Capra?

I haven't had a chance to do any more work on the Capra but I did finally get around to cleaning up my work area a bit. I thought maybe some of you might get a chuckle out of the results. The box in the picture represents a number of spools of filament (I've lost count) and hundreds of hours printing plus I don't know how many hours hand cutting those aluminum frame rails that started all this. I have to laugh at myself because this has really gotten out of hand.
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Old 07-31-2020, 03:21 AM   #18
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Default Re: VFD Capra...Can I Still Call It A Capra?

That’s insane, but kool as hell.
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Old 07-31-2020, 04:36 AM   #19
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Thatís insane, but kool as hell.

Yeah, insane is probably an accurate description...
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Old 07-31-2020, 05:29 AM   #20
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Default Re: VFD Capra...Can I Still Call It A Capra?

You need to start that 12 Step Program...wait, make that the 1,000 Step Program. You'll probably see a lot of us in it.
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