Shock spring compressor

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#1 Post by **mangocrazy** » Mon Jan 19, 2015 10:09 pm

This will probably all sound a bit bonkers, but I'm in the process of getting 5 shock spring compressors built. I wanted one for myself, but the only one I could see that looked a proper job was made by Ohlins, and I didn't even enquire about the price.

I live in Sheffield these days, and the amount of metalworking that goes on there is amazing. In its glory days it must have been mind-boggling. Basically within a couple of miles radius of me there are umpteen steel stockholders, welders, engineers, fabricators, machine shops, laser and water jet cutters, polishers etc. etc.

So I decided to make a copy of the Ohlins compressor, and see if I could get it made in Sheffield. This is the Harris version of the tool, and it still costs £350 + VAT:

http://www.harris-performance.com/acata ... nners.html

Anyway, I decided that I'd make mine in steel. It may be (and is) a lot heavier than ali, but it's also a lot stronger. Top and base plates are in 15mm steel plate, and the columns are 40mm box section steel with 4mm wall thickness. Just the top and bottom plate weigh a ton (figuratively speaking).

When I asked for a quote from the laser cutting company for the bits I needed, I asked them to quote for 1 off, 2 off and 5 off. 2 off was scarcely more expensive than 1 off, and 5 off wasn't that much more, so I took the plunge and ordered 5 sets. They're currently being welded up, and will need plating to finish them off, but I'm thinking I will need to charge around £250 per unit just to cover my costs. This will include everything to start off , including the hydraulic bottle jack and a machined adaptor to take the bottle jack saddle on one side and a recess for the shock top mount on the other. Does this sound a fair price to people?

Photographs once I have a completed version.

Falco Frank · #2 Post by **Falco Frank** » Tue Jan 20, 2015 10:03 pm

Would be good to have a Shock and Fork spring compressor in the same unit. I think.

I use cheapie screw clamps on shock springs, big 19mm nut to tighten, solid but always feels to me, like something might slip one day....

Some other designs for you to consider:

http://racetech.com/page/id/70

Good luck - Frank

#3 Post by **mangocrazy** » Tue Jan 20, 2015 10:38 pm

I think that a shock and fork spring compressor would, by their very nature, need to be different tools. A fork spring is long and thin, a shock spring is short and squat and has a much higher spring rate. I bought a fork spring compressor (for USD forks) a while back and it's a great tool. Only cost about £70 as well.

I've tried removing shock springs before, and have always felt that I was teetering on the edge of something very unpleasant happening. Those screw clamps always look and feel like they're trying to get away from you. Which is why I went for total overkill on this device I'm getting built.

Got the bases back from the welders today - uprights have been tig-welded top and bottom of the base and it's a lovely job. I'm just about to get some pegs made to secure the top plate, and then everything's going off to the platers. I'm intending to have everything electroless nickel plated - it's hardwearing, corrosion resistant, nice and 'slippy' and it looks really good - a bit like a more mellow version of chrome.

I'd have taken pictures today, but it was freezing cold and threatening snow. Perhaps get some at the weekend.

#4 Post by **mangocrazy** » Sat Jan 24, 2015 4:44 pm

Managed to grab a few pics today - the first one is of the base (15mm plate) and two 40mm x 4mm wall box section uprights, with 10mm holes laser cut at intervals of 20mm. Looking chunky...

: DSC_7114_small.JPG (211.04 KiB) Viewed 3455 times

Next pic is a close up of the welding on the top of the base plate that secures the uprights to the base:

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And the last one is a shot of the welding on the underside of the base plate. So the uprights are welded top and bottom of the base plate. I think that should be strong enough...

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#5 Post by **mangocrazy** » Thu Feb 19, 2015 9:21 pm

Finally got all the parts back from the platers today. Haven't had chance to take any pics due to the relentless rain. As soon as I can do so, I'll grab a couple of shots and post them up. Finish (when you can see them) is electroless nickel plating - a hard wearing, corrosion resistant and 'slippery' coating that looks like a warmer version of stainless steel.

John at Revs Racing has expressed an interest in seeing some photos of the setup, so hopefully I'll be able to dispose of the extra parts and cover my costs (which are increasing daily...)

wayno · #6 Post by **wayno** » Fri Feb 20, 2015 8:33 am

I just saw your pics, glad to see you posted the uprights through the base and welded from the underside too, far too many people drop parts on top with a single weld and wonder why they break.

Nice looking bits of kit, can't wait to see the finished article.

#7 Post by **mangocrazy** » Sun Feb 22, 2015 5:35 pm

Finally got a break in the weather on Saturday and managed to grab a few pics. First of all an overall view of the device, being modelled by everyone's favourite - A blue spring Sachs shock. This one has only done about 300 miles since new and that was 300 miles too far...

: DSC_7149_small.JPG (230.09 KiB) Viewed 3454 times

Next up is a view looking down on the top plate and upper fixing pegs:

: DSC_7143_small.JPG (212.69 KiB) Viewed 3454 times

Then a view from the side of the top plate, showing upper and lower fixing pegs:

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Then an up-skirt shot of the top plate showing the lower fixing pegs.

: DSC_7176_small.jpg (123.68 KiB) Viewed 3454 times

And then finally a view of the underside of the base plate:

: DSC_7171_small.JPG (203.78 KiB) Viewed 3454 times

I'm well pleased with the results - I just hope some people are interested enough to put their hands in their pockets for one, or else I'll have a lot of expensive can-crushers lying around the house.... I think the electroless nickel coating really sets the whole thing off.

As you can imagine, with 15mm plate top and bottom and 40x40x4 box section uprights, they weigh a bloody ton. But then they are built like a brick sh1t house...

fatboy · #8 Post by **fatboy** » Mon Feb 23, 2015 7:56 pm

Very nice bit of kit,well designed but maybe a bit specialised for your average owner?

#9 Post by **mangocrazy** » Mon Feb 23, 2015 11:29 pm

Yes, agree FB. They're only really suitable for bike shops or people who are forever fiddling with bike suspension (that'll be me, then...)