Little project: a repair part for a friend

A high school classmate was told her old Crawford garage door opener is not repairable because the plastic clip that failed is no longer
available.
Sure it is, if you know a machinist! But wait, there's more... http://members.goldengate.net/dforeman/gdo_clip /
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good idea, but there is a simpler way to attach - just add a screw and washer underneath to hold it to the chain, or alternatively drill through the link and put a screw or pin to hold it to the chain

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On Mon, 22 Mar 2010 22:13:15 -0700, "Bill Noble"

I haven't seen the installation, it being some 800 miles from here. Your first solution would only work if the underside of the chain is accessable in situ. Your second solution might work if the person on the ladder could dril thru a chain sideplate without snapping a drill bit in the hole. You go first!
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ok, some more ideas - a small piece of spring steel that engages the edges of the chain. What I have actually done in similar situations (not a garage door opener, but similar failures) is to drill the plastic item and add some metal reinforcement - in this case extending the ear with a small piece of wire drilled into the plastic - you are right though if you can't see the installation and are relying on a 'replace or discard" type repairman, you may have limited options. Personally, I don't have a garage door on the theory that if I am too infirm to lift my garage door, I'm also too infirm to mess with whatever is inside.
wrote:

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On Mon, 22 Mar 2010 22:38:34 -0700, "Bill Noble"

You don't have a garage door for fear that you might be too infirm to lift it and use whatever is housed within? A properly balanced garage door can be lifted with one finger by a dainty and comely lass.
Your posited solutions may well be brilliant, we'll never know unless you make them and demonstrate. I'll stay tuned for that.
I'm old school. I back up my words and imaginations with metal that works.
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On Tue, 23 Mar 2010 06:10:16 -0500, "Karl Townsend"

Alibre design. $99 on sale. http://www.alibre.com/
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Don Foreman wrote:

TurboCAD here.
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Pete C. wrote:

You're tough! I waded into TurboCAD twice, learning curb too steep for me.
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RBnDFW wrote:

For the little bit I do it isn't too bad.
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A steal at 99 bucks. I need to renew maintenance and possibly upgrade in a few weeks.
Oh, and nice write up on your project. I enjoyed reading it over coffee and oatmeal this morning.
Wes
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On Tue, 23 Mar 2010 06:10:16 -0500, "Karl Townsend"

I've used AutoCAD for many years. I regard it as an essential shop tool. I don't use CAD software on every project. Sometimes I just make a sketch on a quadrule pad, sometimes I don't even do that. But sometimes CAD's ability to sort out geometry and give dimensions is very useful. Example: on the clip, I needed to determine the radius of the curved part from two measurements: width and height of the broken part. I could figure out how to do that with geometry, trig and a calculator, but AutoCAD makes it very easy because it can draw a circle defined by 3 points. Dimension the circle to get the radius, done.
AutoCAD in 3D, however, is a freakin' nightmare.
Alibre is a parametric solid modeller, like SolidWorks and ProE, at an affordable price. I can see why a professional might want the "real thing" but Alibre does what I want to do in my home shop. It's particularly useful for projects that have a number of parts, including moving parts, that must fit together.
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...

...
I must be older school than you. I would have fit that arc with a compass faster than you could walk to your office and turn the 'puter on.
I do agree, AutoCAD is a necessary tool for complex parts. I may just buy Alibre for my spare time project next fishin' season. About eight years ago, I spent all my spare time from fishin' learning autoCAD.
Karl
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On Tue, 23 Mar 2010 18:53:31 -0500, "Karl Townsend"

The puter is in the shop and it's always on. <G>
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On Tue, 23 Mar 2010 18:53:31 -0500, "Karl Townsend"

Truth be told, using Alibre for this little pissant project was a bit of overkill, not really necessary at all. But I find using Alibre kinda fun, and if I don't use tools like that once in a while I start to forget how to use them. Where Alibre really shines is when designing something with quite a few parts that need to fit together and work together. It's good for playing "what if" because it's a parametric solid modeller. You can change a dimension in a part that's in an assembly, and everything in that assembly affected by that dimension will change in response. When you get your model to your satisfaction, it can then generate dimensioned drawings of every part and assembly. If you later change a dimension in a part, all of the drawings of that part and assemblies affected by that part will be changed accordingly. I think it can also produce output compatible with some CNC systems but I don't really know anything about that.
I once attended a free seminar hosted by the local SolidWorks dealer. I have to say that Alibre is not in the same class as SolidWorks, but SolidWorks is way beyond my play budget at several grand a seat with annual maintenance not optional -- ya gotta pay to play. Alibre does about everything I want to do, albeit not always quite as easily as SolidWorks, and its price was commeasurate with its value to me.
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What's that Lassie? You say that Bill Noble fell down the old rec.crafts.metalworking mine and will die if we don't mount a rescue by Mon, 22 Mar 2010 22:13:15 -0700:

Heck with that. Just clean off the oil and wrap a lump of duct tape around it.
--

Dan H.
northshore MA.
  Click to see the full signature.
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wrote:

That is a very nice solution.
Careful, though, lest it gets out of hand. For instance my neighbor needs a starter shaft for his Shovelhead. I didn't do my surface grinder any good by regrinding a chipped carbide wood shaper bit on it for another friend.
jsw
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Oh, that's cool! The plastic one is work to be proud of, but not leaving well enough alone, you do yourself better with a new design! [Clap, clap, whistle, ...]
I can see that you're well up on the learning curve of the CAD software <G>. A beginner would have spent HOURS making the "drawing". Or, maybe you are a beginner & did spend hours on it (?).
To make installation "... whilst hanging upside down from a rope in a howling gale by flashlight ..." easier, you could use something larger than a 4-40 setscrew. They're pretty easy to lose.
I think it could be a _little_ simpler by not having the middle tooth. I think the plastic one might need it, but not the ally one. Doesn't hurt, though.
Nice write up, too.
Thanks for sharing, Bob
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Don Foreman wrote:

Nicely done! If you're interested in the project for some side income, there's probably a small market. I know in fact there is a market for replacement parts for stuff like this, just can't quite figure out how to reach those that need the diverse parts.
Some time back I was searching for some obscure hardware when I stumbled across a web site that had probably a couple hundred odd fittings and special screws, mostly relating to obscure and decidedly vintage carburetors back to nearly the dawn of the automobile. Guy had spent a fair bit of time coming up with that list of parts and probably is close to, if not in fact, a world leader in supplying these parts.
A significant portion of my income derives from making replacement parts for light rail. Rarely have the luxury of a drawing, often have to work from broken or worn parts. OEM parts are either too expensive, have wicked long lead times, or are just not available anymore. I just made 5 parts out of solid aluminum, 2" thick, 9.5" dia, 5" center hole, lots of detail work. End user was quoted -12 months- for replacement parts. Hell, I could have built a foundry, learned pattern making, cast 5 pieces in my back yard, machined and delivered in less time! While machining was expensive, they had parts in less than 3 weeks.
My customer knows the industry and is my gateway, but there's got to be a need for small lot parts in many other fields....
Jon
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On Mon, 22 Mar 2010 23:22:16 -0500, Don Foreman

Hey Don,
Neat-o stuff from you, as usual. Very good.
We used a similar "ramp" for limit switches, but not on chain. The principle we had might work here though. Looking at the project that you "designed", if you were to make a single piece that had a full end and the rest being half thickness for the remainder, you could place two very easily in a back-to-back pair to make a "whole", including the middle tooth. I suspect that on the original, that middle tooth took all the drive forces, minimal as they might be, so then very necessary.
As this is a fixed length, you might even make it with a hole and a pin in the piece, such that when placed back-to-back, the pin in one locates in the hole on the other, and that would allow placement and locking without screws while up on the ladder. Just snap in place, but the force to do so would be sideways rather than along the chain length as you assume the original is placed.
Our application had the ramp pieces mounted on a slotted rail, and the ramp could be "extended" for adjustment as the micro-switch rode fully over it, and it was the ramped-up distance that was critical. The pieces were identical, same "hand" and all, but when placed looked very much like what your pix and then you sketch showed.
Take care. Keep up the good work and simple ideas you come up with. I'm sure I speak for many if not most of us here on RCM to say that we enjoy them a lot, and always the story and/or detail that comes with them!!
Brian Lawson, Bothwell, Ontario.
ps... I don't know if Mike Rehmus (Model Engine Builder magazine publisher) will once again be doing a Seminar at NAMES 2010 in Southgate, Michigan, next month (April 24 & 25), but at NAMES 2009 if you did attend his presentation, you got a free copy of the base Alibre program. Good deal !! Makes the price of admission seem petty.
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