wh1sp3r

Hello

I created this thread to show my progress. I ordered parts needed for construction and now deciding, which motor to use.
it seems, it will be great to use chainsaw motor becuase it's very cheap.

http://www.hobby-planeta.cz/d/raptor-245-motorova-pila/

45 ccm / 2.1 kW is a lot of power. need to get, how much rpm i can get and make a right gear ratio. Price of this chainsaw is 100€
What do you think about the engine ? I also looked on Zenoah engines, but they are not that cheap

Also, Iam thinking to use own remote control on 2.4Ghz ( Wifi, ZigBee ) for control three servos (steering, gas and brake ).
if some wheel transmitters can control brake as a third servo, it will be better

Lars from Norway

Hi, and welcome here!

The motor is nice, i am using a Jonsered 44 ccm engine in my homemade car. But you have to be prepared to make some custom parts to make it fit though.

What car are you planning to build, onroad or offroad/buggy? Looking forward to see more of your project

Dirty_Vinylpusher

Mounting a drive sprocket on the chainsaw clutch can be tricky.
Do you have access to a lathe and/or welder?

Look for small size chain like the one used in mini scooters and choppers, as it will reduce the size of the sprockets.

Start with figuring out how to mount the motor and then build the car around it.
Use the mounting bolts for the chainsaw bar.
Make sure the mounts are strong as chainsaws are heavy and have lots of torque.

Also leave all the casing on the motor as it's vital for cooling.

I'm not familiar with the Raptor chainsaw brand, but if it was me I'd spend that money on a couple of second hand saws of a better known brand like Stihl or McCulloch.
That way you have some spare parts too, which is always handy.
Most of these cheap chainsaws etc work well the first couple of times you use them but they don't last very long.

Alternatively, if you can find one cheap, a motor from a minibike is a great option as it already has a drive sprocket and is easy to mount.


Look forward to progress pics of your project.

wh1sp3r

Hello Dirty_Vinylpusher

I have access to all machinery like lathe/mill/drill and i plan to use a flame as welder. Problem is, my material is usually aluminium ( tubes, plates ) and welding these materials are hard. i found a special material for welding these materials, so i will see, if it will not work, i will just use screws

I read your topic and i have seen your way or mounting sprocket and problem is, a sprocket for a chain is a bit different. It has space between teeth 8.2XX mm and my chain and other wheels are 8mm so i hope, it will not be difficult to change a sprocket. I saw only chainsaws clutch bells on pictures.

Tommorow, i will check the motor from person, who repairs chainsaws, so perhaps, he will give me a old engine for better price and i have to check other parts like wheels, becuase i don't know, which bearings diameter should i use etc.

I did lots of drawings and everything seems to be ok and possible to make without any problem, but i know, i will have problems hehe
This will be my first large car with full suspension and i am still thinking to make it without it for first time.

What do you think ? what was your first car ? somekind of easy construction or you tried to make it with everything possible ?

Lars from Norway:

i am still thinking about construction .. to make it with suspension or without it. but because i have onroad cars only, i would like to have a offroad

Dirty_Vinylpusher

Yeah try to keep it as simple as possible to begin with.

I've started many projects over the past couple of years and some have been more successful than others.
I used angle grinder and small sprocket and chain for a couple of them:






















This one is a chainsaw motor which I welded a sprocket on to.
I never used it for a car yet but maybe one day:











You can see some of my cars on my YouTube channel > [link=http://www.youtube.com/user/hairyalien]CLICK HERE[/link]

Giorgos_cupra

Welcome to the forum whisper and good luck with your built.

Do NOT built the car without suspension.I understand that for your first built it may seem a little too much,but if you dont you will be disapointed.I know because i did.I have built an on road 1/5 car without suspension and the handling is not that good.

I am now building the second version,with adjustable suspension height,camber,toe in/out and 4wd.

You can see my first built here http://www.rcuniverse.com/forum/m_7677148/tm.htm

wh1sp3r

hehe, hello Giorgos_cupra

i am actually inspired with your first version of car without suspension. It's should not be hard to use it with spring, becuase front part of car has almost same construction. I ordered engine 25 ccm (1,2 HP) for 75€. It's a germeny engine and it should be ok as i talked with chainsaw mechanics. For that price ... it's a very nice engine funny thing is, when i want to buy a new carbuer for it, it costs 120€ so it's better to buynew engine, lol.

When i have engine, i will remake my drawings to fit my engine and i will post some of my construction ideas and photos of engine

Nitro Fumes

Considering its a chainsaw engine at least it has a chain drive too!

Dirty_Vinylpusher

Chains ain't chains


You can't use a chainsaw chain to drive an RC car.
Nor will any other chain fit on the chainsaw clutch.



Chainsaw chain:









Roller chain:








Chainsaw sprocket:








Roller chain sprocket:

wh1sp3r

Today, i was trying to disaasebmly chainsaw, everything went right except clutch !! I can'T get it off , it's very much tightened.

i will go to the service place and i hope, they will help me

Dirty_Vinylpusher

The clutch will be left-threaded.
In other words you have to turn it clockwise to undo it.

I usually sit the saw on the bench, hold a screwdriver against a solid part of the clutch and give it a sharp quick hit with a hammer.
That should loosen it.

Dirty_Vinylpusher

Actually, how does the clutch sit on that saw?
Did the chain run on the "inside" of the clutch - between the clutch and the saw - or on the outside?

If it's on the inside, do as I said above, if it's the other way round there will be a nut on the outside..... yeah?

It would help if you posted a picture of your saw.

wh1sp3r

Hi,
So becuase i have a friend, who repairs chansaws ..it was easier problem was, a clutch was GLUED to shaft, really stupid thing.

Now, i am able to figure out, how to and where to place my engine. Another problem wrong direction of rotation, i have to use two gears.

wh1sp3r

I am drawing a gears at the moment. Trying to find suitable gear ratio. What do you think about gear ratio for me ? motor is only 1.2 HP. it does rpm from 2800 - 11 000. (recommended ) )

Nitro Fumes

I already knew that they aren't the same kind of chains.

Lars from Norway

I had 1:3 gearing on my car which had a Jonsered 36 ccm chainsaw engine with about 2 hp. This ended up in a burned clucth, and the car wouldn't reach its rpm's to get enough torque to again get enough speed. I also used wheels on about 14 cm in diameter. I ended up closer to 1:6 at the end.

Mudgy

turn the motor around (mount it) 180degrees.

Dirty_Vinylpusher

Give yourself the option to change the gear ratio if you need to.
Making calculations on paper is one thing but once the car is on the ground it's a whole different story.

I suggest start building and work out the ratio as you go.
Wouldn't go any higher than 6:1 though.

With "higher" I mean that 5:1 is higher than 6:1.
Motor turns 6 times and the rear wheels turn once.



And....
Are you trying to do all this with only 2 gears? [&:]


I still think sprocket and chain is a better option though.
Or a combination of gears and sprocket/chain.

wh1sp3r

i will use sprocket and chain of course + i wanted to use gears too for changing direction.

hm, ok, i will try think out a good ratio, which can be changed later. it's now all about compromis...

Lars from Norway :

if you burnt your clutch, it looks like, motor has enough power, what about to use a clutch with heavier grapple ? hm, but you propably tried it.

wh1sp3r

ok, i did ratio 6:1 it have done it that way, i can change ratio easily. Of course, this motor can do more rpm than 11 000 .. but it's not recommended, so i will let it default. I am still drawing and making sure, everything is ok and possible without any problem. I have nice shop there, where is everything from machine parts. I will make a proper drawings and show it to you. I need a opinion from experienced people ;-)

Car is 60 cm long and28 cm wide. i would like to make it lighter as possible, but i am not sure, how much will my construction weight at the moment

wh1sp3r

seems, my calculations was wrong, lol. i will use 6:1 to 7:1 ratio of course

ok, first design

Lars from Norway

If i only had the book with the formula on how to find the theoretical speed here now it would be nice Anyway, when i tried to figure out the speed on my car using 3:1 (not 1:3 as i wrote earlier), i found out that the top speed would end up on 160 kilometer per hour and beyond, way too fast and totally uncontrollable!

Seems like your car is actually smaller than 1/8th scale -make it a bit bigger so you don't have to squeeze in every part while wishing the car was bigger I have had problems on my car with wheelbase on 535 mm and a width of 420 mm, but i figures it out in the end

rangerfredbob

My Feedback: (13)

for figuring out the speed, take the diameter of the tires planned multiply it by pi (3.14) to get the circumference. For industrial engines 10000rpm is reasonable for a top rpm but 7000 is more realistic (many magnetos are limited to 7000-7500). Multiply the diameter by the rpm and divide by the gear ratio (if 6:1 use 6 in my equation below) and multiply it by 60 to convert from revolutions per minute to revolutions per hour. This will give you the car speed in the units you used for the diameter per hour, use the proper conversions from those units to what you want...

Diameter of tire*3.14*rpm*60
_________________________
gear ratio

Dirty_Vinylpusher

Trying to calculate the speed before the car is even built is pointless if you ask me.
Build the thing, see how it goes and if you want it to go faster or slower, make modifications to suit.

Calculating speed based on the engine's RPM, gear ratio and wheel circumference is all good and well, but once you add the weight of the car, wind resistance and just the general nature of things - you'll realise that it's not what you thought it would be.


I've seen this before, a number of times.
People starting a thread just like this one.
"This is my engine, this is the car I'm gonna build, this is how fast it will go"
Most of them never even started building and were never heard from again.


I'm not trying to discourage you, but I think you're starting at the wrong end.


Get that motor mounted on a frame with your 4 wheels and see where to go from there.
You have a long way to go before you need to worry about top speed.

wh1sp3r

I am just waiting for my stuff, which i ordered.

so i can kill time with theory, construction i just used to plan before doing everything .. it's part of my job too

Tommorow, i will get alluminium plates and U profiles, screws and other stuff. Next week, i will get sprockets, chain and bearings.
So lots of time to do theory