Thread: Speedglas helmet fix

The problem with the original parts is that they are plastic. I used them as a template, but I must say thinking about it, sketching it and doing it again a few times took a while because I'd realise that once I got to a certain point I might not be able to hold the work to complete the next operation.
So the turning was done first, then I drilled (in the lathe) to 5 mm diameter as I would need to tap a 6 x 1.0 mm thread in both the internal part and then in a knurled nut for the outside.
The "base" is 22 mm diameter by 1.6 mm thick and the next smaller diameter is 14.2 mm turned to a length of 5.4 mm so that the "top" 3.4 mm would be squared off in the mill (10.4 x 10.4 mm). The square part locates into the shell of the helmet.

I used two longer 6 mm SHCS to hold the inner bits for milling. I drilled and tapped a piece of flat steel and screwed them down (had tapped the aluminium parts as well and milled a recess for the SHCS on the inside to a depth of 3.8 mm to have enough thread length on the outside - SHCS 12 mm threads.)
Took off approximately 1.9 mm per side to a depth of 3.4 mm and side length nominally 10.4 mm.
Here's a picture of new versus old with the outside spring washer in the middle.

Here are the last 3 pictures - should make it clearer. And it seems to work fine now, so I can get back to welding. Cheers, Richard

Why can't I ask about the Bultaco?
Russell

Hi Russell,
It's a long story. It was a 1975 Pursang 250. Bought it as a wreck off a farm for $500 in 1995. Spent about #4K on it and sold it in 2002 for $2300. Hey, I made $1800 on it
Sold it because I decided to take up welding and went off to TAFE (Tuesday evenings) and because I really had nowhere to ride it.

That's a nice resto. RP. I have a '78 Alpina nearing completion. I think I will get a pro. to paint the tank & side covers. They were good bikes in their day. ( Note the smilie) . Russell

Hi Russell,
A lot of what you see in that picture was courtesy of Don Newell in Brisbane. I was living in Tamworth at the time. I don't know if Don is still around. I cleaned up the frame and had it powder coated locally. I sourced what I could myself, but Don supplied a lot of bits and pieces and did the motor and gearbox for me. It was slow. Now I would be more confident about tackling it but I guess that's one way to bite off more than you can chew...
My father restored old bikes and some cars, so I got the bug a bit. He had some old Matchlesses among others. I rode his early 1970s Ducati 250 desmo a bit and loved it. All gone now and I'm not sure he remembers any of it.

Meant to say: good luck with the Alpina! Sad to see a number of marques of my yoof gone. Bultaco, Montesa, Maico. Obviously a lot before my time too.

Tidy work on the helmet, Dr Pepper.

Nice fix on the helmet. Just the other week I broke my whole head band, so tossing up whether to fix it or buy a new one as it's only a Chinese one that I have had for 15 years,lol
At the moment it's a hand held one.

Dave

Awesome work on Speed glass helmet I'm going to show those pic's to the Speed glass sales rep next time I see him.

Hi Bryan,
Thank you - although using aluminium was a bit of a cheat as it's so easy to work and getting the finish was easy with an HSS tool bit (1/4" in my Hafco AL340A).
Thanks, Dave. I've been meaning to fix mine for a while. There's another plastic piece on the left side with two lugs that limit fully open and fully closed. One of these started to break and I used a soldering iron to make a (poor) weld. It needs replacing I think. I like your stuff - have been following your posts for quite a while now.
Hi River, thanks for the compliment. It was quite simple really, once I figured it out. I have a lot to learn and I appreciate the efforts put in by others on this forum. I thought documenting this with photos might make it clear to anyone new to machining. (Not that I'm an expert, far from it.) Machining and welding is just a release from my day job, although it's a bit circular. I weld a welding trolley for my welder - that's why I need a welder!
Actually, I do wonder how the Speedglas would fare in an industrial environment. I love my helmet, but it is a bit delicate.

Cheers,
Richard

The pictures a great, and I forgot to say earlier those knurls come up nice. along with the rest of the job.
I am hoping to use one of my spare standard helmet bands to fix mine, but haven't looked at them yet.
It's hard to go back to a standard one after you have been spoiled.

Dave

Thanks, Dave. I have on my project list a scissor-type knurler to make. I had to really push the knurler in hard to get an even knurl on that aluminium, which I don't like doing - although I was using a live centre.
I know what you mean about helmets. I started welding at TAFE in 2002 and came so close to giving up. After week 3 my lovely and generous wife just told me to get an auto darkening type (can't remember the brand about $400, so not cheap). It made a world of difference. The welds were still like chook droppings but at least I could see where I was going. The old helmet went to my son when I got the Speedglas and now he has his own welder and has built an add on tig set up with HF start etc. He leaves me for dead there (electronics etc), but my welds are better for now