Scratch build Nitro tethered race car, second try!

[WickedFog]

You're having too much fun. That keyway turned out beautiful.

 

[johnnydmd]

Impressive machine work and project!

 

[Roog]

Thanks everyone, I'm not sure I would describe it as fun! I was quite daunted by the keyway, as I hadn't cut one before, I have the two rear wheels to attach to the rear shaft, buoyed up by this experience I might try this method for those too.

I have said this before, many of the elements of working are new to me, I am trying to introduce them rather than find a work around which is what I have done in the past.

 

[CertifiedMike]

Thanks everyone, I'm not sure I would describe it as fun! I was quite daunted by the keyway, as I hadn't cut one before, I have the two rear wheels to attach to the rear shaft, buoyed up by this experience I might try this method for those too.

I have said this before, many of the elements of working are new to me, I am trying to introduce them rather than find a work around which is what I have done in the past.

You can't be scared of the unknown once its all known!
Even if its not ALL fun, its been a lot of fun to watch you diving in "head first"!
Taking on and completing new challenges, fails along the way, is what learning is all about!
Thanks for letting us ride along!

 

[Roog]

Thanks Mike, I think the stress comes from the risk of making a mistake and wasting a days work, plus the expense of metal going into the off cuts pile.

Luckily it doesn’t happen too often, but getting the key way width wrong was embarrassing, it would have taken seconds to check but because I thought I knew better. My loss on this occasion was just the key itself.

 

[CertifiedMike]

Thanks Mike, I think the stress comes from the risk of making a mistake and wasting a days work, plus the expense of metal going into the off cuts pile.

Luckily it doesn’t happen too often, but getting the key way width wrong was embarrassing, it would have taken seconds to check but because I thought I knew better. My loss on this occasion was just the key itself.

Actual material loss is unfortunate.
I tend to look at some or that stuff as "spares" or "donors" for the next build.
I am an old guy. Often I'll do a familiar job by diving in instead of reading up first to remind myself of the little things. When I forget things, I have to re-do some level of assembly because I forgot a little pin or clip. Something silly but important!
Not entirely the same scenario but its a reminder to "measure twice, cut once", be thorough.
I usually find them more humbling than embarassing because I feel like, "I've got this, no prob!"
Your embarassment is likely much further than I could have reached so consider that too!
I feel like I'm learning even though I'm not actually working by reading your posts!

 

[Roog]

Actual material loss is unfortunate.
I tend to look at some or that stuff as "spares" or "donors" for the next build.
I am an old guy. Often I'll do a familiar job by diving in instead of reading up first to remind myself of the little things. When I forget things, I have to re-do some level of assembly because I forgot a little pin or clip. Something silly but important!
Not entirely the same scenario but its a reminder to "measure twice, cut once", be thorough.
I usually find them more humbling than embarassing because I feel like, "I've got this, no prob!"
Your embarassment is likely much further than I could have reached so consider that too!
I feel like I'm learning even though I'm not actually working by reading your posts!

It very good of you to say this, I have dialled back the step by step detail and my thought processes because I felt it came across as patronising, and a bit too drawn out, all this despite the fact that I am learning this stuff as I go along. I really am just trying to ‘logic this out’ rather than knowing what I’m doing!

 

[CertifiedMike]

It very good of you to say this, I have dialled back the step by step detail and my thought processes because I felt it came across as patronising, and a bit too drawn out, all this despite the fact that I am learning this stuff as I go along. I really am just trying to ‘logic this out’ rather than knowing what I’m doing!

When I'm "mathing" something in my head, I do an awful lot of "outside" talking!
Your process is very interesting to me but I appreciate the time involved to detail each step.
Kids will be playing with flying saucers before the thread finishes if it goes too deep!
I'm sure what you do post will be equally interesting and educational!

 

[Roog]

When I'm "mathing" something in my head, I do an awful lot of "outside" talking!
Your process is very interesting to me but I appreciate the time involved to detail each step.
Kids will be playing with flying saucers before the thread finishes if it goes too deep!
I'm sure what you do post will be equally interesting and educational!

I'll do my best :0)

 

[Roog]

Today I added the chassis rails I was hoping to get slightly narrower’C’ profiles but ended up with a sort of square section, it quite light so I can live with it. It involved a bit of sawing facing off square in the mill and drilling for the mounting screws, nothing particularly interesting but critical to keep the thing square.

They also may need shortening but as they say you can cut excess off but it’s hard to add it back on.

Next are the bits which are to hold the front wheels on. I’m going for a fixed axle as seems to be the standard arrangement with soap box go-cart style steering. Ok it’s not steering per se it’s a trim to help it smoothly get around the circuit if required.

First is a fairly chunky cross connecting lump, but the plan is to fit it between the rail C section and then remove what I can to get the weight down. First face off both ends to make a rectangular solid

Then reduce the top surface for a tight fit between the C on each side.

Next remove the centre, reducing the thickness so that the centre hub can sit down within it and support the front wheel shaft at the correct height

Because the chassis rails partially coincide with the shaft height I will have to cut away a section of the rail around the front shaft. This is an irritation but I am hopeful that the sturdy cross member will hold what remains of the front section Of rails which simply need to support the front of the body work. Part of the cross member needs to be cut away to allow the front axle to swivel a few degrees.

it will look tidier once I’ve cleaned it up, but more importantly it has lost a fair bit of weight

Next up is the swivel front axle hub.

Starting by facing off a block, then drilling the hole for the front shaft.

Then reaming the hole to its final size, probably not necessary but it was easy with the mill locked off in position

Then on to drilling the shaft/axle retaining screw and the very simple swivel axle which will be an M5 screw done up tight. I’ll fit a smaller set screw in the cross member below to lock the swivel in place. First using a centre drill to guide the twist drills in to the right place. No need to centre punch, just touch off from three sides of the block and wind the mill table to each position according to the digital readout then drill. The DRO is probably the single most effective way of improving the accuracy of my work. All of the milling operations on the cross member where done with no setting out or marking the piece, just touch off three faces and calculate every move from one corner or centre line on the piece.

 

[Roog]

Here are the cross member and swivel hub in their relative positions, the swivel requires some more material removed and both parts require more holes for assembly and fitting to the chassis.

 

[Doom!]

Your not finished with this yet? just teasing, looks good, like watching the progress.

 

[Roog]

Your not finished with this yet? just teasing, looks good, like watching the progress.

Thanks @Doom! progress is painfully slow, plus I’m feeling quite tired, standing all day in my shed in the cold.

Already thinking about what I need to do tomorrow, bit daunted tbh, large material removal in my small milling machine is tough, nerve wracking!

 

[Doom!]

I can understand that, getting the big stuff out of the way can be tedious, a bit more fun when you get to the fine tuning.

 

[Roog]

On a positive note we have the body work to come!

Ferrari 375 ish is the plan

Aluminium is tricky to join, so tin plate perhaps?

Either way, if I can’t find a ready made body shell there is going to be a lot of hammering of metal over a wooden plug

Could be fun, I’ve not tried this before.

 

[Roog]

Removing some metal where it’s not needed

Temporary fitting

Next fitting it into the chassis rails, needed several taps with a small mallet to get it in. Then mill the top of the C section to make way for the axle

Drill the assembly and bolt together before tidying up the edges

And at last the assembled chassis

Cleaned up, it’s starting to look like a bit of engineering!

I think it has to be wheels and axles next.

 

[Roog]

Ok I have found a line drawn picture of a Ferrari 375 with some sections shown, this could be quite tricky!

I have superimposed my chassis drawing on it and it looks like it might fit.

And just for laugh here is what Ai recon it might look like, some hope!

Anyone know if there is a 1/8 scale body shell for this car? Help!

 

[johnnydmd]

What's the wheelbase?

 

[Roog]

What's the wheelbase?

Good point, 10 3/4” and the max width of the chassis is 2 7/8”(not including the axles which I haven’t decided yet but scaling off the drawing gives 7 3/4” width at the tips of the axles)

 

[johnnydmd]

So that's about 270mm, a little bigger than typical 1/10 touring car body scale. Just wondering what type of body might be out there for that. Might be something to get made custom.