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Re-engineering the Shift Spring


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Just talked with the guys at the spring company. It seems their manufacturing tolerances are not quite as tight as Chuck's experience. However, we have sorted it out and they are making a new batch of

Yeah, grumble about the bit being too long (but that's better than too short).  However, there's no way I'm sending out any springs that cannot be installed as-is. While I appreciate the offers of hel

Anywhere someone is allowed to express their opinion. While we think of this as detrimental it's actually a key component of crowdsourcing. If you get enough people expressing their perspective you wi

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This is up in my office, but there is 3 more images and the titles are slightly different. Give me a day or two and I'll post it. It brings me back to the real world really quick when things go awol.  

 

 

large_020517_treeswing.jpg

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Ok, I see the problem. Scud sent me some springs to check. See the red line on the cad drawing and the box at the top left saying length .7?

26114341638_bf2572a211_c.jpg2018-01-30_10-23-08 by Charles Stottlemyer, on Flickr

My bad. I intended to tag the end of the line when dimensioning it, not the center of the spring. That's why when I scaled the spring I'd made for the last time before sending the whole works back to Scud I marked out the .62 dimension and said .7  :rolleyes:  There is no excuse for that. Sorry.

Just the same, it would work ok. It just sits there and doesn't move through the full travel and more. Here is the assembly at coil bind.

25116262907_fd2e273879_c.jpg2018-01-30_10-25-42 by Charles Stottlemyer, on Flickr

However, the angle is way out of spec. We asked for 15 degrees, and you can see it is 31. 

39088678715_55b3f6c3ea_c.jpg2018-01-30_10-24-55 by Charles Stottlemyer, on Flickr

That is unacceptable because it will drive the spring past it's "safe travel." My gut feeling is if the manufacturer could wind another 15 degrees on it, they would be ok.

Just the same, I'd like to make another run and make everything *right* including the ID of the spring. I asked for .660/.670" and it is .682. Again, that shouldn't hurt anything.. but it's out of the spec that was calculated. It will apply a (very) little less torque.

Maybe they will give us a break on another run because of one of the most important specs being out of tolerance?

There's a reason for that swing set cartoon.. :oldgit:

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However, the angle is way out of spec. We asked for 15 degrees, and you can see it is 31. 

39088678715_55b3f6c3ea_c.jpg2018-01-30_10-24-55 by Charles Stottlemyer, on Flickr

That is unacceptable because it will drive the spring past it's "safe travel." My gut feeling is if the manufacturer could wind another 15 degrees on it, they would be ok.

Just the same, I'd like to make another run and make everything *right* including the ID of the spring. I asked for .660/.670" and it is .682. Again, that shouldn't hurt anything.. but it's out of the spec that was calculated. It will apply a (very) little less torque.

Maybe they will give us a break on another run because of one of the most important specs being out of tolerance?

There's a reason for that swing set cartoon.. :oldgit:

 

Hi Chuck, as we say in the Netherlands, "waar gewerkt wordt vallen spaanders". Free translation: those that do the work, are more likely to make mistakes than those that do nothing.

So, I stepped in and will support you guys all the way, even if it is only on a distance and with the cost for the springs etc.

I personally favor the solution according to spec. and am willing to pay for it. However, I also agree with you about the small difference in length, reducing the force only 10% and the wrong angle being the real bugger (more spring tension).

 

I wonder what the spring bender will say. Time and machine are probably more a thing than the material.

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Time and machine are probably more a thing than the material

Oh, yeah. The material is essentially free. All the money is in the time to make them.

I should have just stepped up and made them in the first place. They would have been done and forgotten about by now. It just reminded me entirely too much of work.. and.. a place that does this commercially should be tooled up and be able to make them for considerably less than I can.

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Time and machine are probably more a thing than the material

Oh, yeah. The material is essentially free. All the money is in the time to make them.

I should have just stepped up and made them in the first place. They would have been done and forgotten about by now. It just reminded me entirely too much of work.. and.. a place that does this commercially should be tooled up and be able to make them for considerably less than I can.

 

Its all good Chuck, mistakes are made. Lets see what the spring guy says, Now he knows that the customer will be doing the QC he might be a little more focused on getting the specs spot on.

 

Ciao

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Ok, sounds like we are close to taking the next step. On the inside diameter... If I recall correctly, the drawing gave a minimum, but not a maximum, diameter. 

 

I can send the springs back in a few days - I'm away from home right now. 

 

Chuck, I'll need a revised drawing, you can e-mail a pdf to me.

 

 

waar gewerkt wordt vallen spaanders.   :luigi:   :D 

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waar gewerkt wordt vallen spaanders.   :luigi:   :D 

Dear me, and I thought our motto was "The Ride Starts Here!"

 

I should have a banner made for my shop:

 

:luigi:   "The Mistakes Start Here."  :luigi:

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waar gewerkt wordt vallen spaanders.   :luigi:   :D 

Dear me, and I thought our motto was "The Ride Starts Here!"

 

I should have a banner made for my shop:

 

:luigi:   "The Mistakes Start Here."  :luigi:

 

Best shop banner ever.

 

 

 

High quality

Fast service 

Cheap cost

 

Choose any two

 

 

 

Ciao

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Ok, sounds like we are close to taking the next step. On the inside diameter... If I recall correctly, the drawing gave a minimum, but not a maximum, diameter

 

I can send the springs back in a few days - I'm away from home right now. 

 

Chuck, I'll need a revised drawing, you can e-mail a pdf to me.

 

 

waar gewerkt wordt vallen spaanders.   :luigi:   :D 

No, I said .660/.670"  on the marked up original drawing.

IMG_7490.jpg

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Ok - so I just need to be sure they understand the min/max on the ID.  That wasn't clear to me, but I don't know the "secret handshake" of engineering drawings. And I'll strike the strike that.

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Ok - so I just need to be sure they understand the min/max on the ID.  That wasn't clear to me, but I don't know the "secret handshake" of engineering drawings. And I'll strike the strike that.

Just want to re-acknowledge the fine work you and Chuck are doing here Scudd. This all takes time and communication and checking and re-affermation and its a process. Thanks again chaps.

 

Ciao

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Thanks Phil. I/we appreciate that.

I was going to post last night, but was kind of upset about what I found when I started seriously checking the spring as delivered.

The wire diameter is correct.  :rasta:

Just kidding.. there is more that is correct. The location of the bend on the long arm is good. 

I decided to wind another 15 degrees on one..

39110803795_17414d4267_c.jpg2018-01-31_02-35-10 by Charles Stottlemyer, on Flickr

You can see how much longer the short arm is than the sample I gave them.. no matter that I screwed up and tagged the wrong place when dimensioning. 

Installed it on the shifter gizmo, and measured.

39125017905_d6497e49e2_c.jpg2018-02-01_10-28-20 by Charles Stottlemyer, on Flickr

You can see that even if they went to the center of the spring, it's at least .100" longer than spec.

How about that bend radius? .11" minimum was specified..

39125416285_f85cb08e47_c.jpg2018-02-01_10-52-54 by Charles Stottlemyer, on Flickr

They no doubt just wound it around a commonly available 3/16" pin. This is a 3/32 radius gauge.

Let's talk about standard manufacturing tolerances. Angular is normally plus or minus 1/2 degree. 15 degrees?? Hello. Earth calling. Single place decimals, plus or minus 1/32". Two place decimals plus or minus 1/64" inch.

Almost every manufacturing job has things that matter and things that don't. Now, what really "matters" on this job?

Wire diameter. Check

Inside diameter of the spring. .660 to .670 was specified.. it is .682. It's not rocket science to get it right.

The angle. It could be plus or minus a couple of degrees. That's easy enough to do. 15-16 degrees out? No

Length of the long arm to the bend. Check. That puts it in the right location to ride properly on the boss on the pawl.

Length of the short arm. Not really as important, although it is off from what was specified, too.

Minimum bend radius. I called for .11"  .11-.015 tolerance.. .094. (3/16") Ok, close enough.

Picking the fly shi  stuff out of the pepper  :)  the long arm is crooked as a dawg's hind laig..

39991669952_8f1af50f44_c.jpg2018-02-01_10-53-41 by Charles Stottlemyer, on Flickr

 

 

My personal feeling is they just didn't take any pains to get it right on such a small job. Even an amateur spring maker like me can  :angry2:  and *will* if they can't. 

I took the time to make a proper engineering drawing to send to Scud with my phone number if the manufacturer wants to talk to me. I'll get it out today or tomorrow.

 

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Thanks Phil. I/we appreciate that.

I was going to post last night, but was kind of upset about what I found when I started seriously checking the spring as delivered.

The wire diameter is correct.  :rasta:

Just kidding.. there is more that is correct. The location of the bend on the long arm is good. 

I decided to wind another 15 degrees on one..

39110803795_17414d4267_c.jpg2018-01-31_02-35-10 by Charles Stottlemyer, on Flickr

You can see how much longer the short arm is than the sample I gave them.. no matter that I screwed up and tagged the wrong place when dimensioning. 

Installed it on the shifter gizmo, and measured.

39125017905_d6497e49e2_c.jpg2018-02-01_10-28-20 by Charles Stottlemyer, on Flickr

You can see that even if they went to the center of the spring, it's at least .100" longer than spec.

How about that bend radius? .11" minimum was specified..

39125416285_f85cb08e47_c.jpg2018-02-01_10-52-54 by Charles Stottlemyer, on Flickr

They no doubt just wound it around a commonly available 3/16" pin. This is a 3/32 radius gauge.

Let's talk about standard manufacturing tolerances. Angular is normally plus or minus 1/2 degree. 15 degrees?? Hello. Earth calling. Single place decimals, plus or minus 1/32". Two place decimals plus or minus 1/64" inch.

Almost every manufacturing job has things that matter and things that don't. Now, what really "matters" on this job?

Wire diameter. Check

Inside diameter of the spring. .660 to .670 was specified.. it is .682. It's not rocket science to get it right.

The angle. It could be plus or minus a couple of degrees. That's easy enough to do. 15-16 degrees out? No

Length of the long arm to the bend. Check. That puts it in the right location to ride properly on the boss on the pawl.

Length of the short arm. Not really as important, although it is off from what was specified, too.

Minimum bend radius. I called for .11"  .11-.015 tolerance.. .094. (3/16") Ok, close enough.

Picking the fly shi  stuff out of the pepper  :)  the long arm is crooked as a dawg's hind laig..

39991669952_8f1af50f44_c.jpg2018-02-01_10-53-41 by Charles Stottlemyer, on Flickr

 

 

My personal feeling is they just didn't take any pains to get it right on such a small job. Even an amateur spring maker like me can  :angry2:  and *will* if they can't. 

I took the time to make a proper engineering drawing to send to Scud with my phone number if the manufacturer wants to talk to me. I'll get it out today or tomorrow.

Well thats disappointing Chuck. I normally like to give the benifit of the doubt but not much care taken here. Its very common these days and I'm running accross it ALL the time to the point its depressing.

A case in point. I have a brand new Focus RS with 1100klms on it and Ford has just issued a "customer satisfaction action" to mine and 27000 other Rs's to have the head gaskets replaced due to them fiting the wrong ones in assembly. I wont even go into that here. Checking the workshop manual this is quite a big job to do insitu. The whole front of the engine needs to come off, engine mount,cam chain cover, cam chain and tensioner, even the oil pump drive, then of course the turbo, the Hi pressure fuel pump, vacuum pump etc etc and then you get to pulling the head itself.

Interestingly this engine doesnt have a single keyway on anything, cams front cam chain sprocket, engine pully, it relies on friction to hold it all in place. So I'm thinking with all of this I need to trust my brand new car to a Ford dealer tech to pull the engine half to pieces.Hmmmm..........I'm thinking, looks like I have some work to do. I'm not even going to claim warranty on this, I'd rather eat the cost and know its done right. This spring story just confirms my thoughts on getting things done right these days. 

Lets hope the spring guy steps up this time and they take the care to get it right. 

 

Ciao

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