Scratch build electric tethered car racer

[Roog]

I haven't exceeded 64mph that I set last time :0(

But yes I have an excuse to muck about in my workshop (shed) again, if only I didn't have to finish a couple of house jobs over the next couple of week ends.

 

[ahr43]

Congrats, Roog. At 64mph, you've well made entry into the 100kph Club.

 

[Roog]

Congrats, Roog. At 64mph, you've well made entry into the 100kph Club.

Now why didn't i look at it that way? I've reached a ton!
I like your thinking @ahr43

 

[Roog]

The torture that is insulating and boarding out my house loft and fitting a loft ladder is now ended, phew!

Today I have mostly been making new wheels to fit the commercial tyres I have acquired.

Wheels not quite finished but close, now I need to make a new drive shaft because the old one, pictured isn’t long enough for the new hubs which are a little wider than my previous wheels to accommodate the new tyres.

New ‘design’ ha ha, has just one cap head screw to hold each wheel together and keep it on the shaft!

This could be interesting.

 

[WickedFog]

The torture that is insulating and boarding out my house loft and fitting a loft ladder is now ended, phew!

Today I have mostly been making new wheels to fit the commercial tyres I have acquired.

View attachment 188247

Wheels not quite finished but close, now I need to make a new drive shaft because the old one, pictured isn’t long enough for the new hubs which are a little wider than my previous wheels to accommodate the new tyres.

New ‘design’ ha ha, has just one cap head screw to hold each wheel together and keep it on the shaft!

This could be interesting.

Are you doing reverse threads on the passenger side (driver's side for you guys across the pond )?

 

[Roog]

Are you doing reverse threads on the passenger side (driver's side for you guys across the pond )?

Oh come on that would be proper engineering, no I’m relying on conventional threads and lots of high strength threadloc :0)

 

[WickedFog]

Oh come on that would be proper engineering, no I’m relying on conventional threads and lots of high strength threadloc :0)

That's scary! At least mill a groove in the wheels to locate on a pin through the axle. I'd really hate to see a wheel fly off. I really don't think thread loc is not going to hold it with all that power.

 

[Roog]

I think I misunderstood, yes there will be a slot in the hub, just as my previous efforts albeit to accommodate a thicker pin this time. I hadn’t quite finished the hubs when I took the photo.

I’m currently thinking 2.5 or 3mm pins, my concern is the larger the pin the less metal remains in the 8mm diameter shaft at the pin hole. With my previous runs I have seen no issues with wheel screws undoing, just tires trying to escape!

I do agree I probably should invest in reverse threading taps and screws, I expect I did do this correctly back in my days in the apprentice training centre but not since.

You raise an interesting point though, in all of the wheels and car plans I have looked at very few incorporate such drive engagement, perhaps the engineering guys do the reverse thread thing.

 

[Roog]

New wheels on my wagon and it rolls along very nicely

New hubs are a little thicker than my last wheels. It was a concern that I was able to distort my old wheels during tightening and I felt I could afford slightly greater thickness due the the reduced diameter of the new hubs

 

[Doom!]

I think your going to see a decent improvement on your next run.

 

[Roog]

I think your going to see a decent improvement on your next run.

Well I hope so! Next track day is week after next so I have a while to find out.

It would be good to get full throttle in without things trying to escape. Ultimately that will be the test.

 

[Weezel]

I'm glad you caved in to peer pressure on using molded tires.

Those tires are going to be much better than what you had. They should allow you work on the chassis and gearing set-up to improve speed rather than worrying about not getting a good run in.

Looking forward to your next test

Does your cable connection point need to be where it is or can you put it anywhere? I was thinking how much the chassis might twist? With the center of gravity being higher than the mounting point and everything (battery,motor,esc) mounted on the high side of the aluminum angle I'm thinking it'll induce chassis roll.

 

[Roog]

I'm glad you caved in to peer pressure on using molded tires.

Those tires are going to be much better than what you had. They should allow you work on the chassis and gearing set-up to improve speed rather than worrying about not getting a good run in.

Looking forward to your next test

Does your cable connection point need to be where it is or can you put it anywhere? I was thinking how much the chassis might twist? With the center of gravity being higher than the mounting point and everything (battery,motor,esc) mounted on the high side of the aluminum angle I'm thinking it'll induce chassis roll.

The offer of some molded tires came out of the blue, the track owner seeing my frustration said, “hang on I’ve an idea” he wandered back to his workshop and came back with a pair of tires.

Its a bit awkward but I am currently having trouble sourcing some replacements here in the UK.

One other issue is that now I have them on their hubs, I can see that they aren’t truly round, so they are going to need grinding before use. :0(

My current tether connection has a strap across the top and a lower one preventing the turning out, this causes extra wind resistance and weight so I might revert back to one attached to the lower position, a set up which worked during the first ‘ton-up’ run (ha ha..)

As you say it would be good to focus on the tweaks to make it faster.

 

[Roog]

Just few small bits of work this week, I ground the new tires round which took a 1/16” off them and I changed the tether connection which I hope will help to keep both rear wheels more equally loaded when hard up against the tether.

The tether pivot is higher than the car connection point.

 

[WickedFog]

Just few small bits of work this week, I ground the new tires round which took a 1/16” off them and I changed the tether connection which I hope will help to keep both rear wheels more equally loaded when hard up against the tether.

The tether pivot is higher than the car connection point.

View attachment 188778

View attachment 188779

I hope your front tire holds up now once you get the speed up. I would try to tighten up that support cable. Can you add an adjustable link in it somewhere? Like add one of these at the mounting point on the chassis...

I'm just thinking if the weight balance is off, the back end of the car (likely being a lot heavier) can get pulled farther outward and cause instability with that support cable having slack in it. An adjustable support there could compensate for that.

Or maybe even something like these, to utilize the same style ends you have on your current cable.

 

[Doom!]

@Roog I really admire you skills for crafting parts on this build.

 

[Roog]

@Roog I really admire you skills for crafting parts on this build.

Thanks @Doom! its all a bit of an experiment for me, I was taught the rudiments of turning at school, back in the days when they let you do such dangerous things, and went on to be taught the basics of mill work, turning surface grinding and welding during a very short (4 month) stint at my first employer’s apprentice training centre over 40 years ago. In recent times I have learned a lot from YouTubers and as long as I take it easy with my small machines and don’t break too much it is reasonably logical and within the reach of anyone who is prepared to apply themselves, I mean I find it easier than teaching myself how to play guitar! Now I wouldn’t post my efforts at that on the web.

I hope your front tire holds up now once you get the speed up. I would try to tighten up that support cable. Can you add an adjustable link in it somewhere? Like add one of these at the mounting point on the chassis...
View attachment 188783
View attachment 188781

I'm just thinking if the weight balance is off, the back end of the car (likely being a lot heavier) can get pulled farther outward and cause instability with that support cable having slack in it. An adjustable support there could compensate for that.

Or maybe even something like these, to utilize the same style ends you have on your current cable.
View attachment 188784

Hi @WickedFog I like those rose joints and turn buckles, I could use those to adjust and angle of the tether strap by adjusting the length of one side of the triangle, I like it!, but perhaps you are referring to the stranded safety tether wire? That is left slightly loose so that I can change the attachment point. You pass the tether carabiner through the fixed tether strap hole then though the safety, the idea being that if the bolts holding the main strap in place come loose the safety will hold the car until it crashes out on the Grass ‘in field’ it is normally baggy and not in tension.

The track owner asked me to add these to my heavier than normal cars following my first visit with my IC powered car. :0)

 

[WickedFog]

Thanks @Doom! its all a bit of an experiment for me, I was taught the rudiments of turning at school, back in the days when they let you do such dangerous things, and went on to be taught the basics of mill work, turning surface grinding and welding during a very short (4 month) stint at my first employer’s apprentice training centre over 40 years ago. In recent times I have learned a lot from YouTubers and as long as I take it easy with my small machines and don’t break too much it is reasonably logical and within the reach of anyone who is prepared to apply themselves, I mean I find it easier than teaching myself how to play guitar! Now I wouldn’t post my efforts at that on the web.

I started off in my dad's wood shop at 9 years old, cutting out teddy bears, birds, and rocking horses for a guy whose wife painted them up. They travelled the flea markets selling them. I made a lot of money doing that.

My first ecperience with metal shop was in middle school. I made a dust pan lol. Later, I took vocational (a 2 hour class) metal shop in high school. It wasn't til in my 20's that the woodworking experience got me a job at a shop that had CNC routers. That experience plus my metal shop class landed me a job at an aerospace machine shop. 10 years later, I was basically doing the work of a prototype machinist/cnc program engineer/tool maker. I designed and made fixtures to hold and machine some really complex prototype racing parts for IndyCar and NASCAR assemblies.

These were for one of the IndyCar teams. $10,000 shock body with SUPER tight tolerances, and some really hard to machine features. They started off as an 8" diameter billet bar as seen in second pic.

 

[Roog]

I started off in my dad's wood shop at 9 years old, cutting out teddy bears, birds, and rocking horses for a guy whose wife painted them up. They travelled the flea markets selling them. I made a lot of money doing that.

My first ecperience with metal shop was in middle school. I made a dust pan lol. Later, I took vocational (a 2 hour class) metal shop in high school. It wasn't til in my 20's that the woodworking experience got me a job at a shop that had CNC routers. That experience plus my metal shop class landed me a job at an aerospace machine shop. 10 years later, I was basically doing the work of a prototype machinist/cnc program engineer/tool maker. I designed and made fixtures to hold and machine some really complex prototype racing parts for IndyCar and NASCAR assemblies.

These were for one of the IndyCar teams. $10,000 shock body with SUPER tight tolerances, and some really hard to machine features. They started off as an 8" diameter billet bar as seen in second pic.
View attachment 188789
View attachment 188790

You see @WickedFog you are a proper machinist,I am merely playing at this.
But it is interesting to hear how people get into their respective careers.
I love CNC but being a cheap skate I am less keen on the amount of metal which is removed. Lovely resultbthough and strong. Perhaps one day metal 3D printing will be able to do this for the masses?

 

[WickedFog]

You see @WickedFog you are a proper machinist,I am merely playing at this.
But it is interesting to hear how people get into their respective careers.
I love CNC but being a cheap skate I am less keen on the amount of metal which is removed. Lovely resultbthough and strong. Perhaps one day metal 3D printing will be able to do this for the masses?

You are doing a fantastic job with this man. One thing I noticed from the get go is your surface finishes look great. Especially for not having flood coolant. Your design is solid too. One thing I excelled at, and why I progressed to the prototype work in every shop I was at, was because I could see areas of fixtures that would be at risk of mechanical loads and stresses. Some of the parts I made were ones people thought we couldn't do til I designed a fixture. So when I point out things on your build, it's just me being a bit over analytical. You've done a great job at building something not many people could build.