Author Topic: how to lighten BS springs? (Read 16150 times)

wellington1869 · « **Reply #50 on:** Sun, 02 August 2009, 16:19:08 »

thanks, i'll see what i can find out there...

wellington1869 · « **Reply #51 on:** Sun, 02 August 2009, 23:30:45 »

ok, these two sites (recommended at an RC hobby site) look really promising (for small parts in general, including things like O-rings):

http://www.smallparts.com/
http://www.mcmaster.com/#

I just started poking around there right now...

update: ok, mcmaster has a size spring that is pretty close but the load resistance is way too high (around 1 lbs). But reason for optimism: price is about $6 for pack of 5.
for reference thats Part Number: 9435K13

update: at the smallparts.com site, the closest one I found is this:
http://www.smallparts.com/Stainless-Steel-Inst-Spring-Length/dp/B001DID5FK?ie=UTF8&qid=1249274526&pf_rd_r=1ZEDQM08DEMAFSXXHHWC&pf_rd_p=467590031&pf_rd_i=0&sr=1-51&pf_rd_s=center-3&pf_rd_m=AIUBT5HP6PMAF&pf_rd_t=301
basically its dimensions are right, but I dont know if the resistance is right. The only resistance listed is a "spring rate" of .8 inch-pounds. I havent a clue what that means. When you convert 55g (an example 'target' resistance) to lbs, it comes out as .1212 lbs. But is that the same as 'spring rate'? I doubt it. So I'm not sure what to ask for even if I called them. Any ideas?

IN terms of all the other dimensions (wire thickness, length, and width), the spring is in the ballpark.

JBert · « **Reply #52 on:** Mon, 03 August 2009, 09:36:05 »

Quote from: ripster;106249

Here it is in inches.

Unicomp oddly enough is exactly the same. Coil count too. May be a slightly different metal though. Other factor is the foot - different plastic - I need to do a more complete comparison there.

Indeed, if the wire diameter, spring size and coil count are the same, the only thing remaining is the spring material (or there was a measure error when looking at the wire diameter).

Do they make their springs themselves? If so, they can probably tell if they changed the type of steel.

wellington1869 · « **Reply #53 on:** Mon, 03 August 2009, 09:44:35 »

well it doesnt look like cost will be an issue, most of the "replacement springs" i've seen so far have been relatively affordable (about a dollar per spring).

timw4mail · « **Reply #54 on:** Mon, 03 August 2009, 09:45:46 »

That can get rather expensive when you're replacing 101 springs, though.

timw4mail · « **Reply #55 on:** Mon, 03 August 2009, 09:49:01 »

Quote from: ripster;106400

I got the impression from that DIY Spring site that most small springs are made of "music" steel. The same stuff in my guitar strings. Probably SOME variance though.

Yeah, I was going to comment on the cost. My $20 Boscom will net me 122 springs - that is the cheapest deal going if you wanted to renovate an old mushy M.

I can't imagine that the consistency of the spring steel would have been a very important factor for IBM/Lexmark/Unicomp. Its like plastics, you have a slightly different batch each day that in the end performs about the same.

wellington1869 · « **Reply #56 on:** Mon, 03 August 2009, 12:03:41 »

Quote from: timw4mail;106399

That can get rather expensive when you're replacing 101 springs, though.

true, though personally i'd only replace the main alphabet cluster. so i'd spend about 30 bucks. I dont think its worth doing it for all 104 keys unless i had that kind of disposable income.

wellington1869 · « **Reply #57 on:** Mon, 03 August 2009, 12:04:51 »

i'd order some to try but I'd like to know more about its resistance. I'm too unfamiliar with the terminology being used to indicate the resistance levels. Need to find out more.

talis · « **Reply #58 on:** Mon, 03 August 2009, 15:48:32 »

I just took a few measurements of the springs from my 401.

Length : 18.5mm
OD : 2.75mm
ID : 2mm
Wire dia : .18mm (33 gauge)
Buckling point : 4.8mm compression @ 68g

As far as I could measure, the compression force seems to be fairly linear at about 15g/mm

wellington1869 · « **Reply #59 on:** Mon, 03 August 2009, 15:53:44 »

Quote from: talis;106610

I just took a few measurements of the springs from my 401.

Length : 18.5mm
OD : 2.75mm
ID : 2mm
Wire dia : .18mm (33 gauge)
Buckling point : 4.8mm compression @ 68g

As far as I could measure, the compression force seems to be fairly linear at about 15g/mm

talis, can you take a look at this link? In terms of dimensions, I think its about the right size - but in terms of resistance level, I havent a clue.

talis · « **Reply #60 on:** Mon, 03 August 2009, 16:29:12 »

Unless I screwed up the conversion (very possible) 15g/mm translates to about .83 lb/inch. Seems to be almost exactly what that spring you linked was rated.

I used my jig, a dial indicator, and a scale to take those measurements so they may not be 100% accurate either.

wellington1869 · « **Reply #61 on:** Mon, 03 August 2009, 16:30:57 »

Quote from: talis;106648

Unless I screwed up the conversion (very possible) 15g/mm translates to about .83 lb/inch. Seems to be almost exactly what that spring you linked was rated.

hmmm, that would be a pity, because .83 was the lightest one they had. Wouldnt make any sense to get the exact same spring...

so the search continues I guess...

it might be worth getting one or two of those just to make sure. If we're lucky the compression characteristics would be slightly lighter (putting it in the 55-60g range). But tahts really just a shot in the dark I guess.

talis · « **Reply #62 on:** Mon, 03 August 2009, 16:38:42 »

To compute the spring force (and I'd love it if someone would double check this math) you'd take the force you want and :

Force * [(25.44mm/inch)/(4.88mm * 453.59g/lb)]

That assumes the spring will buckle at exactly the same point (which is independent of the spring force as far as I can tell).

Theoretically to get 60g of actuation force you'd want a spring force of .689 lb/inch. Again that assumes that it buckles at 4.8mm of compression (which is not really a safe assumption to make).

wellington1869 · « **Reply #63 on:** Mon, 03 August 2009, 17:04:40 »

Quote from: webwit;106661

Hmm..
http://www.leespring.com/uk_intro_LP_compression.asp

fascinating. Who wants to buy-n-try?

wellington1869 · « **Reply #64 on:** Mon, 03 August 2009, 17:13:49 »

oh they have a selector where you plug in mm and it tells you which spring to buy:
http://www.leespring.com/uk_compression_spec.asp?springType=C&forWhat=Search

timw4mail · « **Reply #65 on:** Mon, 03 August 2009, 18:29:51 »

Hmm...I don't have the proper tools, but does anybody know the specs for the Model F springs?

wellington1869 · « **Reply #66 on:** Mon, 03 August 2009, 18:35:34 »

so if no one wants to buy-n-try the light springs, am I going to have to sacrifice my only son, er, my only model M keyboard because I so loved the world (of keyboarding)?

wellington1869 · « **Reply #67 on:** Mon, 03 August 2009, 18:39:36 »

Quote from: ripster;106705

I sacrificed a Boscom and managed to sleep fine.

yes but was it your only begotten boscom? this is my only begotten model M, and I will have to forsake it, and it will be set upon and killed, verily.

talis · « **Reply #68 on:** Mon, 03 August 2009, 21:53:33 »

Quote from: wellington1869;106706

yes but was it your only begotten boscom? this is my only begotten model M, and I will have to forsake it, and it will be set upon and killed, verily.

Who knows, tearing it apart could motivate you to start working on your own mod!

(Still a work in progress).

wellington1869 · « **Reply #69 on:** Mon, 03 August 2009, 22:05:32 »

Quote from: talis;106737

Who knows, tearing it apart could motivate you to start working on your own mod!
Show Image

(Still a work in progress).

thats beautiful :)

I dont need the arrow cluster either.

That with 60g springs = perfection?

lal · « **Reply #70 on:** Tue, 04 August 2009, 07:18:48 »

Indeed, looks promising. Now if you could make the cuts a) invisible and b) indestructible...

wellington1869 · « **Reply #71 on:** Tue, 04 August 2009, 10:37:40 »

Quote from: lal;106796

Indeed, looks promising. Now if you could make the cuts a) invisible and b) indestructible...

you could probably make it pretty undetectable if you fill the seam with caulk and paint over it.

itlnstln · « **Reply #72 on:** Tue, 04 August 2009, 10:55:18 »

Quote from: wellington1869;106849

you could probably make it pretty undetectable if you fill the seam with caulk and paint over it.

I would use something harder like Bondo. That way you could sand it down and paint it a little easier. Caulk would be too rubbery, I think. The only thing that might be lacking with any method of filling and painting would be matching the texture of the original case. That could be a whole new mod (refinishing/rebuilding the case).

itlnstln · « **Reply #73 on:** Tue, 04 August 2009, 10:56:18 »

I like the title of the pic, too. The "Clacky Hacker."

talis · « **Reply #74 on:** Tue, 04 August 2009, 11:40:43 »

Quote from: itlnstln;106862

I would use something harder like Bondo. That way you could sand it down and paint it a little easier. Caulk would be too rubbery, I think. The only thing that might be lacking with any method of filling and painting would be matching the texture of the original case. That could be a whole new mod (refinishing/rebuilding the case).

I'm using a 2 part epoxy putty. Give a bit of structural strength that Bondo doesn't (it becomes less brittle when set).

http://polymericsystems.com/epoxies-adhesives/epoxy-putty-sticks/quikplastik.htm

Still a long way to go on it.

itlnstln · « **Reply #75 on:** Tue, 04 August 2009, 11:43:26 »

Quote from: talis;106894

I'm using a 2 part epoxy putty. Give a bit of structural strength that Bondo doesn't.

Still a long way to go on it.

Good choice. Epoxy putty is awesome stuff. Especially when you have a leak in your car's radiator, and you're waiting for a replacement part.

A little personal experience there.

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Author Topic: how to lighten BS springs? (Read 16150 times)