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How to make a slop-free pivot for a pivoting fence

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Forum topic by GregD posted 1210 days ago 1513 views 0 times favorited 8 replies Add to Favorites Watch
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GregD

612 posts in 1761 days


1210 days ago

Topic tags/keywords: jig question tablesaw

I am making a crosscut sled similar to this one from Rockler and the Dubby from In-line Industries.

Any suggestions for how to make the pivot for the fence so that there is no slop?

The fence is actually a discontinued Rockler aluminum router table fence, but essentially an aluminum angle about 1/8” or 3/16” thick.

My best idea so far is to use a flat head bolt in a countersunk hole through the base of the fence. I am hoping that the bevel on the bolt head will help keep the hole in the base of the fence centered around the bolt. I would then need a tight hole through the sled base to keep the bolt snug relative to the sled base. I suppose I would use a T nut in the base, or maybe a threaded insert.

I’m not sure how I will countersink the hole in the fence. The countersink bits that I have cut rather slow in wood, and using them to drill aluminum won’t help that. I was hoping it would be good enough to use a standard 1/2” drill bit to put just a bit of a bevel at the top of the hole rather than a proper counter-sink.

Thoughts? Comments? Suggestions?

Thanks for your help!

-- Greg D.


8 replies so far

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DonH

483 posts in 1442 days


#1 posted 1210 days ago

Hi Greg

I have built a couple of pivoting fences and vertical alignment is critical to keep all square. If your fence is a right angle I would suggest infilling with wood in the area of the pivot so that you have a solid block in the pivoting corner that attaches to both the vertical and horizontal components of the right angle. Drill this and the table below to accomodate a bushing through which the pivoting rod will reside. I allow the pivoting rod to project above the block and use a leftover piece of bushing around it to keep it from dropping. In my projects you will find a drill press based thickness sander that uses this methodology (although my fence was solid material and not a right angle). This should work well and is easy to do. In my case I found brass rod for the pivot that fitted tightly into copper pipe used for the bushing.

Hope this helps

Don

-- DonH Orleans Ontario

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GregD

612 posts in 1761 days


#2 posted 1210 days ago

Thanks Don. Yes, that is likely to work much more reliably than what I had in mind. Now I just need to find material for the bushing and rod…

-- Greg D.

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DonH

483 posts in 1442 days


#3 posted 1210 days ago

Hi Greg

Any metal shop should be able to help you out.

Don

-- DonH Orleans Ontario

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DrDirt

2399 posts in 2367 days


#4 posted 1210 days ago

Yep agree with Don – Might also try a bearing – like from a 1/2 inch rabbeting bit and bed it in epoxy – but some kind of sleeve/bearing/bushing design is needed to get the tight fit for rotation you want.

-- "If we did all the things we are capable of doing, we would literally astonish ourselves." Edison

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GregD

612 posts in 1761 days


#5 posted 1206 days ago

I found some 1/4” steel dowel pins at the local Ace Hardware. I am guessing that these are more dimensionally accurate than say 1/4” steel rod. I also found some 1/4” ID bronze bearing sleeves. The dowels fit just a bit loose in this sleeve. I suspect these are intended for rotating shafts.

I carefully drilled a 1/4” hole in a piece of 1/8” scrap aluminum. Like the bearing sleeves, the dowels fit just a bit loose in this hole.

I think if I’m going to get really fussy about this pivot point I will need to either find some appropriately machined metal bearings, or make a split bearing that can be snugged up against the dowel.

From the pictures of the Rockler unit it looks like they just use a 1/4” bolt and threaded knob as the pivot.

A simple option – a variation of my original idea – is to use a 1/4” flathead bolt through the base from the bottom and into a drilled/tapped hole in the base of the aluminum fence. I would think that snugging up the bolt should remove the play in the pivot.

-- Greg D.

View JJohnston's profile

JJohnston

1577 posts in 1916 days


#6 posted 1206 days ago

I hate to belabor it, and I’m not a shill, but try McMaster-Carr (www.mcmaster.com). They have steel rod and bushing stock with diameters and tolerances shown. You can get a really nice fit if you choose correctly. I got a smooth rod and matched bronze bushings for a perfect fit on my flip-top planer stand. One caveat on these: the diameter of the galvanized rod is apparently based on “before galvanizing”, because it was too big for the bushing I chose, but the bare rod fit.

-- "Sorry I'm late. Somebody tampered with my brakes." "You should have been early, then."

View Fuzzy's profile

Fuzzy

289 posts in 2613 days


#7 posted 1206 days ago

Shoulder bolt ???

-- - dabbling in sarcasm is foolish … if you’re not proficient at it, you end up looking stupid … ... ...

View GregD's profile

GregD

612 posts in 1761 days


#8 posted 1206 days ago

I was not familiar with McMaster-Carr. Exactly the kind of stuff I was looking for. Thanks.

-- Greg D.

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