Parallel guide rail - work in progress

[John2532]

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Here is my attempt at a simple yet reliable parallel guide rail. I thought I had scored big when I found a fairly robust adjustable T-square at HD. The head locked in the 90 degree position and seemed solid.  Unfortunately, once I machined the adaptor and put everything together I found that the head would loosen when stressed. I'm now working on a slider that will enclose the "T" and hopefully keep everything square.
I'll post more pics when I get it all figured out.

P.S. Would anybody be interested in this design if it works well? Price will depend on what I have to use for the new rail and slider but should be around $150.

 

[sw1211]

I would probably be interested, depending on the final design and price.

 

[fshanno]

How about rigging it to work with something like the Incra Track and shop stop?  This would yield a true stopped rip with repeatable accuracy down to the 32nd.  Squaring would have to be handled at the guide but it looks like you've got that covered already. 

 

[Dane]

That looks good.  I have a question though.  Last week I posted about my system using those same squares.  I chose to use them without trying to hook them to the rail because I was concerned that trying to square up all four points would be problematic.  Those drywall squares are pretty accurate, but not perfect and I am sure that whatever head you machine will be the same way.  Do you run the risk of squaring the heads to the rail and then having any lack of accuracy in the squares cause them to not sit flush on the material edge and screw up your measurement?  Maybe it's not a big deal, but that's the concern that I had when I started using mine.

 

[John2532]

Thanks for the input guys, it is appreciated.

Just to be clear, I am trying to make this work with only 1 unit. I'm confident it will work with the 55" rail and hopefully with the 110".

fshanno,
I'm not familiar with those tracks but looking at them I think it would take 2 of them to make it work. With one I'm afraid the square rail might allow flex and the problem of attaching a suitable "T" still remains. I do like their adjustment system though. If a person already was using the rails it could be cost effective but if it was just for this application I'm not sure it would be feasable.

Dane,
I checked the "T" end of the square and it was surprisingly straight. I could only get a .002" feeler gauge under one end while it was on a machined surface. I might have gotten lucky though. Whenever you can buy something that at least 2 vendors have marked up, and is still cheaper than the raw materials purchased locally, you have to keep your fingers crossed. Your concern is valid though. Even if the edge is perfectly straight, any debris between the edge and the wood could induce errors.
Your method is definately straight-forward and it will be hard to top with a reasonable price tag.

Please keep the ideas coming, I'm trying to justify to my wife that I need another machine in the garage!

Thanks,

John

 

[fshanno]

Just to be clear, I am trying to make this work with only 1 unit. I'm confident it will work with the 55" rail and hopefully with the 110".

A single unit?  Just like a table saw fence, one setting.  Well, it's a noble ambition and I hope it works but I'll be floored if it does.

Also, the scaling on the drywall tee is not good enough.  I need a rule with 16th inch increments and a sighting system that eliminates parallax error.  I'm using the two-rules-clamped-to-the-sheet method now and getting 1/64" accuracy over 8'.  It's just slow and a little tedious.

 

[Dane]

Ah, I didn't get that you were only using one.  That makes more sense.  I am excited to see how do, keep us posted.

 

[John2532]

fshanno,

The drywall square is just being used to see if this is at all feasable. The original markings would not be used.

Thanks,

John

 

[kgearhardt]

How about rigging it to work with something like the Incra Track and shop stop?  This would yield a true stopped rip with repeatable accuracy down to the 32nd.  Squaring would have to be handled at the guide but it looks like you've got that covered already. 

Just an FYI but you can purchase the 6" pieces of the Incra 1/32" sawtooth racks for a reasonable price ($2.50 each including the nuts/bolts for mounting them).  I've purchased a bunch for putting together a miter saw table setup and other measuring systems, though I haven't gotten around to using them yet.  But you could build your own indexed parallel guide on the cheap using those pieces.  I just called Incra and the sawtooth racks should be available through their online store in the next few weeks.