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Robitronic Scalpel 1/18

Old 06-19-2008, 01:39 PM
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BigTb17
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Default Robitronic Scalpel 1/18

Hi everyone. I just picked up a Robitronic Scalpel. I searched and I didn't see any threads on it so I thought I'd start one.

I picked up the kit yesterday from my LHS and will be building it tonight (hopefully). I'll post up pics of the build if I can. It seems like it will be a quick little car on indoor tracks, should be fun. I was surprised how small it is. I have other 1/18 scale cars, but the chassis for this one fits in the palm of my hand. Can't wait to start building it.

Anybody else have one of these? Post it up.
Old 06-19-2008, 04:39 PM
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TheIronMaiden
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Default RE: Robitronic Scalpel 1/18

Seems like a sweet little car. Make sure you get some pictures up whenever its finished
Old 06-19-2008, 05:12 PM
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BigTb17
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Default RE: Robitronic Scalpel 1/18

I started building it and it looks like I will have to make a trip to the hobby shop before I can finish. The chassis accomodates two different servo sizes, neither of which I have. The ones I have are too big or too small. Technically I have a sub-micro which would fit just fine, but I don't have any servo horns that work with it.

Oh, well. Hopefully I will be able to finish it tonight. Here a few pics.

Here is the chassis next to my RC18T to give you an idea of its size.




Old 06-19-2008, 05:21 PM
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Default RE: Robitronic Scalpel 1/18

Looks like a sweet onroader. Who's motor is that? Im liking the gunmetal can its in lol.

edit: looks like theres a decent amount of factory option parts available
Old 06-19-2008, 05:22 PM
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Default RE: Robitronic Scalpel 1/18

[X(]WOW thats nice[X(]
Old 06-19-2008, 05:22 PM
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Default RE: Robitronic Scalpel 1/18

By the way. So far everything seems to be excellent quality. Fit and finish is superb, everything seems very precise and well made. No complaints so far, I'll update the pictures and performance report once I get everything together.
Old 06-19-2008, 05:25 PM
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fm2h3
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Default RE: Robitronic Scalpel 1/18


ORIGINAL: BigTb17

By the way. So far everything seems to be excellent quality. Fit and finish is superb, everything seems very precise and well made. No complaints so far, I'll update the pictures and performance report once I get everything together.
You Better
Old 06-19-2008, 05:30 PM
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Default RE: Robitronic Scalpel 1/18


ORIGINAL: Mousesi2k

Looks like a sweet onroader. Who's motor is that? Im liking the gunmetal can its in lol
It is a E-Flite Park-370 motor (with the blue E-Flite sticker peeled off). The motor mounting location is very tight and this motor is almost the largest possible (20mm diameter, 30mm length). The motor fit exactly (literally zero extra room lengthwise). The motor shaft actually rubbed in the back where it stuck out less than half a mm. I had to dremel a half a mm out of the left axle mount to keep it from rubbing.
Old 06-19-2008, 05:33 PM
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Default RE: Robitronic Scalpel 1/18


ORIGINAL: fm2h3

[X(]WOW thats nice[X(]
Thanks!
Old 06-19-2008, 05:36 PM
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fm2h3
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Default RE: Robitronic Scalpel 1/18

Theres no Diff??????[&:]
Old 06-19-2008, 07:21 PM
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Matt_Gruizinga
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Default RE: Robitronic Scalpel 1/18

I was thinking of getting one of those once i finish my rc18t project, know i'll have to get one.

what wheels are those on your T, the look sweet!
Old 06-19-2008, 09:14 PM
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BigTb17
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Default RE: Robitronic Scalpel 1/18


ORIGINAL: fm2h3

Theres no Diff??????[&:]
It has a ball diff. The spur gear also acts like the diff gear in any other tranny. It actually works really well, surprisingly smooth.
Old 06-19-2008, 09:20 PM
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Default RE: Robitronic Scalpel 1/18


ORIGINAL: Matt_Gruizinga

I was thinking of getting one of those once i finish my rc18t project, know i'll have to get one.

what wheels are those on your T, the look sweet!
They are 1/10 HPI sedan wheels, [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXM945&P=0]these[/link]. I like the look, plus they are just about the cheapest 1/10 sedan rims.
Old 06-19-2008, 09:36 PM
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TheIronMaiden
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Default RE: Robitronic Scalpel 1/18

that red alluminum looks so good.
Old 06-19-2008, 09:38 PM
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Default RE: Robitronic Scalpel 1/18

Here are a few more pics. The chassis is complete, but I still have to trim and paint the body (and obviously I still have to straiten up the wiring). I soldered up a 4 cell saddle pack and am charging it as I type this. I'm interested to see how the Mamba/brushless will work with a 4 cell setup. I always have a couple small 3 cell Li-Po batts I can try to make fit if I have to[>:].







Old 06-19-2008, 10:28 PM
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Default RE: Robitronic Scalpel 1/18


ORIGINAL: TheIronMaiden

that red alluminum looks so good.
Yea that is what i was thinking[X(]
Old 06-20-2008, 04:43 PM
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BigTb17
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Default RE: Robitronic Scalpel 1/18

Well I just got to run it briefly. Last night it got dark before I got a chance to take it out.

I just got home from work and had to try it out, but I didn't run it very long, maybe 5-10 minutes. It does pretty well on the 4 cell pack. It cogs a little, but nothing bad at all. Just a little twitching getting going, but once it is moving even the slightest bit it is perfectly smooth. It isn't going to break any speed records by any means, but it would probably be fast enough for a tight indoor track.

My biggest problem was that the included foam tires got very little traction on the smooth, dusty pavement I was running on. Anything under half throttle was ok, but the rear would break loose very easily. Over half throttle was almost impossible, the rear tires would break loose with the slightest twitch of the steering. Full throttle was impossible, the tires would instantly break loose and the car would spin out. I never got a good idea of the true max speed because no matter how carfully I eased the throttle in it would eventually pass a point of no return and the rear tires would start spinning wildly (even in a strait line).

At half throttle or less it was fairly tame. It handles very well. The steering is very precise and it reacts more quickly and consistantly than any other R/C I have had. The chassis is very well balanced with the saddle pack. As long as I wasn't too crazy on the throttle it was very neutral and even its slides were very consistant and predictable. I can't wait to get it on a surface that suits it better. I may also try to get a different foam compound for times when I feel like taking it for a couple laps here again (my apartment parking lot). The handling may also improve once I mount the body.

For as low as it is the chassis is surprisingly un-marked considering the veerry imperfect nature of the pavement I was driving on. A couple of the screws that aren't countersunk quite flush have a few scrapes on them, but the chassis is practically untouched. This is despite accidentally (followed by one intentional[>:], because it was cool) ramping of a speed bump. It is a fairly small speed bump, but I was still surprised how well it took it. The motor was slightly warm after the run, but that may simply be because the surface of the pavement was probably over 100 degrees from the sun (the motor is only 3 mm above the pavement after all).

Half way through the run I realized that the nut and little white spring which adjusts the tension on the rear suspension/motor mount was missing. Miraculously I found both rather quickly and I tightened it down most of the way for the rest of the run to keep from loosing it again. I will probably put some heavy grease or something on the threads to keep it from rattling loose in the future.

I will run it more later, but I just had to try it out.
Old 06-20-2008, 04:57 PM
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Default RE: Robitronic Scalpel 1/18

By the way, sorry for the long read.

Short version: Handles really well, decent speed on 4 cell but nothing crazy, pavement I tried it on was too dusty for the foam tires to get any traction at all (not really driveable above half throttle due to wheel spin). Very responsive and consistant.
Old 06-20-2008, 11:20 PM
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Default RE: Robitronic Scalpel 1/18

I just got done cleaning the diff. Since the spur gear is basically also the diff gear it is fairly easy for dirt to get into the diff. It is very easy to disasemble to clean, so I figured I'd clean it considering how dusty the area was that I was driving in.

While looking the car over I realized that I broke a part on my run!. Apparently tightening that adjustment nut down wasn't the best idea (neither was accidentally spinning backwards and hitting a curb, which is most likely what did it). The small aluminum stud that the rear motor pod/suspension rides on snapped off at the base. It is hollow and is threaded inside and out, so it isn't really designed to take impacts. I guess you could call it a weak point. However, if I hadn't tightened that nut down it may have had enough movement to absorb the shock and may have been ok. Also, if I had the body mounted it probably would have taken the impact and left the car unharmed. Either way it is a $2 part, which is a pretty cheap weak point to find. It is also very easy to replace. I literally had it out in about 30-60 seconds (three hex screws).
Old 06-21-2008, 05:16 PM
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Default RE: Robitronic Scalpel 1/18

Well, I installed my $1.40 replacement post and it's ready to go. I also soldered up another 4 cell pack and trimmed the body. I'm in the process of painting it now.

I also got the aluminum friction plates (to replace the plastic ones) and bought a few other spare parts. I spent about $10 for everything.

Edit: I guess I'm one of the only ones with this car. If anybody else has one or gets one post it up. Maybe this could be changed to the "official" Scalpel thread.
Old 06-21-2008, 06:43 PM
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Default RE: Robitronic Scalpel 1/18

I have one and its put together but not properly setup yet.
Im working out the turnbuckle lengths on the front for a good setup and using zip ties and an rc18 pack to power a sidewinder/42 combo.

Ill post more once Im happy w/ the setup.

So far, I am very happy w/ the price/quality ratio.
I have a brp that I think will be tougher but lacks all the red aluminum bling.
Old 06-21-2008, 06:43 PM
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Default RE: Robitronic Scalpel 1/18

Does it tell you in the manual what foam is used for the tires? they almost look like they should be "indoor" foams vs "outdoor". The picture just makes it look like they are super super soft. Also, you could consider some tire sauce to make them a bit "stickyr"
Old 06-21-2008, 07:08 PM
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Default RE: Robitronic Scalpel 1/18


ORIGINAL: Mousesi2k

Does it tell you in the manual what foam is used for the tires? they almost look like they should be "indoor" foams vs "outdoor". The picture just makes it look like they are super super soft. Also, you could consider some tire sauce to make them a bit "stickyr"
Yeah, it came with medium in the front and super-soft in the back. They have hard, medium, soft, and super-soft available at the LHS for it. I may try some different combinations and maybe tire compound, but I think my biggest problem was simply the super smooth, painted, dusty pavement. On the concrete sidewalk it hooked up much better (though there is no room to really drive it on short sidewalk).
Old 06-21-2008, 09:11 PM
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Default RE: Robitronic Scalpel 1/18

I just drove the car at the tennis court near my appartment, which was much more suitable. This car is awesome.

It rained a good part of the day and there were small puddles dotting the court. Althouth the car was great at dodging the puddles, after 15 minutes or so I figured I was tempting fate so I stopped. I was curious what my runtime would be like with my IB1400 4 cell I put together. The pack tested 5.3 volts after the run, and hadn't lost much power towards the end. Not bad at all (I wasn't taking it easy either).

I currently have it geared 14/49. The motor was barely above ambient temperature, so I'm sure I could go up a tooth or two on the pinion. The batteries and ESC were also completely cool. I'm glad to now I'm not stressing any of the electronics. I like to know that if I start a race I can push my car as hard as I need to without worring about anything.
Old 06-22-2008, 09:54 AM
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Default RE: Robitronic Scalpel 1/18

In case anybody is still paying attention (I'm the only one still posting), here are a couple more pictures. I finished painting the body yesterday and cut the mounting holes this morning now that the paint is dry. I still have to decide what I want to do with the rest of the decals and lower the body mounts. I may get another body some day and cut the wheel wells a bit smaller. I don't know why the body has such huge wheel wells, but it makes the wheels look tiny. It will look a little better once I lower the body some.




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