Aram
Member
Registered: 01/04/04
Posts: 2938
Loc: Danville, CA
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After repeated issues with store bought Miter Sliders, my next TS sled will use UHMW glides. Should I drill and tap for the screws, or just drill pilot holes and screw directly into them?
Thanks.
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Best,
Aram
"Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away.” Antoine de Saint-Exupery
Web: http://awacs.smugmug.com/Woodworking
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fredhargis
Member
Registered: 08/21/03
Posts: 5622
Loc: Waynesfield, Ohio
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Sounds like you want to screw though the sled into the UHMW. I would suggest you do it the other way, drill a pilot hole and countersink in the UHMW, and then screw through it into the sled.
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Beer is proof that God loves us and wants us to be happy...(Benjamin Franklin)
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Hank Knight in SC
Gloaty McGloat pants
Registered: 05/26/05
Posts: 1321
Loc: Columbia South Carolina, USA
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I agree with Fred: put the screws through the UHMW into the sled from the bottom. If you tighten flat head screws significantly, they will deform the UHMW a little and it will bind in the miter slot. I fixed this by shaving the deformation down with a shoulder plane.
Another tip: UHMW is nearly impossible to glue, so getting it placed accurately on a sled and holding it in place while you screw it down is a trick. I found a very strong 3M contact cement in a tube called Scotch Weld that will tack UHMW down and help make the process easier. The bond is not strong, but it's strong enough to allow you to drill and/or screw the UHMW to a substrate.
Hank
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Rick L
Member
Registered: 04/29/04
Posts: 1029
Loc: Easthampton MA
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Fred has a better answer however UHMW is kind of squishy and will mushroom.
I don't understand why everyone thinks UHMW is the answer. PVC is slippery, denser and harder and makes a better sled bar
I would recommend steel bars and you can put ball nose spring plungers to take up slop...
http://www.mcmaster.com/#ball-plungers/=hxknt3
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Kudzu
Member
Registered: 02/11/05
Posts: 3328
Loc: Heart of Dixie
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Rick L said:
I would recommend steel bars and you can put ball nose spring plungers to take up slop...
http://www.mcmaster.com/#ball-plungers/=hxknt3
They are spring loaded so the slop is still there. You can still move the miter bar in the slot, it's just a little more difficult.
A solid bar with a good fit would more accurate.
As for material I use whatever I have handy in the wood stack. Oak is preferable but any hardwood will work. UHMW is fine and if have some scraps will use it, but wood is free.
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I have found how much a boat is used is inversely related to how much it weighs.
Kudzu Craft Lightweight kayaks
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JGrout
member
Registered: 08/04/02
Posts: 23291
Loc: Axial CO
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Aram:
I use Kreg miter bars instead of UHMW. The reason is that UHMW will eventually wear and become loose forcing you to replace them.
The kreg bars have plugs of plastic in them that wear but allow readjustment for a tight fit in mere moments. For instance my shaper cope jig uses this bar and it has to be dead on for accurate cutting
Kreg miter bars
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Aram
Member
Registered: 01/04/04
Posts: 2938
Loc: Danville, CA
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Thanks, Joe. I've been using Incra's version, and they are great little devices right until the moment that they go all loose and screw up my bed rails.... 
I figured the UHMW would wear gradually, at least. I'll look into the Kreg ones.
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Best,
Aram
"Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away.” Antoine de Saint-Exupery
Web: http://awacs.smugmug.com/Woodworking
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Jeff B
Member
Registered: 12/18/06
Posts: 1155
Loc: Los Angeles, Ca
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JGrout said:
Aram:
I use Kreg miter bars instead of UHMW. The reason is that UHMW will eventually wear and become loose forcing you to replace them.
The kreg bars have plugs of plastic in them that wear but allow readjustment for a tight fit in mere moments. For instance my shaper cope jig uses this bar and it has to be dead on for accurate cutting
Kreg miter bars
+ 1
Jeff
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It seems my best designs are born of my mistakes - or is it my best mistakes are born of my designs?
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Bøb
Member
Registered: 10/13/06
Posts: 1296
Loc: S.E. Tennessee
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UHMW eventually wears ... well ... DUH !!! Most anything eventually wears, but that is not the reason I don't use it for that application ... UHMW "moves" tremendously with temperature changes ... one day loose .. next day tight ... WAY more trouble than it's worth. And, believe me, I was very disappointed to discover THAT little factoid after carrying home hundreds & hundreds of pounds of that stuff out of the trash at work !!!
Fortunately, I also carried home LOTS of LEXAN ... now THERE'S a material for runners & slides. Easy to machine to close tolerances .. thermally stable .. UV resistant .. BULLETPROOF (always a nice thing) .. just plain GREAT material.
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Now let us retract the foreskin of misconception and apply the wire brush of enlightenment.
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ned
Member
Registered: 08/23/02
Posts: 8510
Loc: atlanta GA USA
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Hank Knight in SC said:
Another tip: UHMW is nearly impossible to glue, so getting it placed accurately on a sled and holding it in place while you screw it down is a trick.
Hank
A very easy trick. Lower your blade below the table. Put your runners in the slots, hanging out the back, set your sled over them and screw them down. Move everything forward until the runners stick out the front and repeat. Trim the bulges as necessary for a snug, nonbinding fit. Fine tune by tightening/loosening the screws. Remove the sled, raise your blade and cut most of the kerf. Square and attach your fence (that's another thread) and cut the rest of your kerf as needed.
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A man has a right to his own opinion, but not to his own facts- Jack Spong
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