Template sander collar question

[bdsmith1]

Finally got this template sander made. Shout out to Johnson machine shop and Clark. My only question is on the tolerance of the collar. Do those of you with these machines ever get them dialed in exactly? and if not, what's the tolerance you guys work with?  Clark will make me another rub collar, but Im just not sure how much i should stress the exactness of the match. You can see the spot where I'm grinding the upper half of my template down.  Just worries me.  Does the sandpaper wear in and lose thickness?

[Kirkll]

You'll have much better luck using 36-40 grit paper on those pattern sanders...

another trick is making sure you use a thick base that rides on the bearing or guide so you don't have to run the paper too close to the bearing or guide. If that sand paper drops down over your bearing or guide it will screw up your pattern very quickly.

[bdsmith1]

good note.  I've got a sheet of 3/4 ply I'm going to start making templates from.  Actually working on the CAD for them as we speak.  We put in spacers above the motor cap, then added washers to lift the table up a bit to give me some flexibility in terms of the thickness of the spacer.  The current rub collar is 1/8" thickness, but I think I take some of the washers out and may go to a 1/4" rub collar instead. 

[Crooked Stic]

I use 60 grit belts and my guide wheel .090 smaller than the drum wit a belt on it. I use plexiglass base on my jigs running against the guide wheel . I have a professional made jig that has brown phenolic base. Courses may be better but mine is built for 60 grit.

[bdsmith1]

Hey Stic, do you have a picture of your setup handy?  If it's a smaller rub collar, does that mean that you're losing a bit of your template to the sander where its lifting your stock up to the sand paper?  I may be misunderstanding. 

[bdsmith1]

by the way, it's hard to see it from that first close up picture, but about half of the width of my template is catching the sanding drum.  Its hard to see because I'm sanding a scrap peice of stud 2x4 (spruce I think) so it blends in.

[Crooked Stic]

I had the drive drum turned flat in the center and about except for an inch on top and bottom. So I build my jigs with thick bases to get my work on the flat part of the drum. Mine is a guide wheel not a collar.

[Kirkll]

I use 60 grit belts and my guide wheel .090 smaller than the drum wit a belt on it. I use plexiglass base on my jigs running against the guide wheel . I have a professional made jig that has brown phenolic base. Courses may be better but mine is built for 60 grit.

Those jigs that Brandon built for us used 1/4” Micarta for the base like this stuff.

https://www.eplastics.com/-250-x-36-x-48-X-Sheet?inv=1&customer_id=813-364-8639&gad_source=1&gclid=Cj0KCQjwqIm_BhDnARIsAKBYcmv800dniZgfcMrvbOcTVTER20dvW21qFoLhmpkWIyX5EOXQHwvX7ywaAlz3EALw_wcB

I too have built a number of my own jigs using 1/4” plexiglass and it works ok… but the micarta is much harder and holds up better.

When building jigs without a CNC system, I’ve found the best stuff to work with is 1/4” MDF board for fitting, then sanding  out a permanent base from plexiglass or micarta. the soft linen phenolic won’t work well.

 Another product that could make a good guide base for your patterns would be polycarbonate plastic. That might even  be better than plexiglass.    Any type of canvas / epoxy base phenolic would work well too.

Your sand paper thickness will change depending on the grit you use. The heavy 36 grit cuts easier with the least resistance and pressure against the bearing or guide, but it will cut deeper than 60 grit too…. I don’t really think it matters too much as long as you use the same grit each time.

What does make a difference on complex footing shapes is the thickness of the accent line material you use. So if you have a CAD system and are designing a shape, you need to factor in the thickness of your accent line material. I believe Brandon used .060 so you can use 2 .030 accent lines and have a perfect fit.

Another thing that needs to be factored in when building footing jigs is building a matching set of rough cut out jigs for the riser block with location pins or dowels that allows you enough space to cut between the lines with your band saw. These S shaped footing jigs are not easy to build by hand.

The perfect fit is very important on footed risers. If you are having to use clamps to tighten up your joints on a footing,  it’s building stress into the riser that could come back to haunt you…. Food for thought……

[bdsmith1]

So I have a xcarve CNC and 3d printer in the shop that I can make parts with, just not out of metal. I'll probably use a lot of MDF and cabinet grade ply for templates since they're in my range to cut. I've tried acrylic, but it turns into a mess pretty quick as I don't have figured out the right feeds and speeds not to melt it.  I've been using my cutting template to mark, but I saw your flared riser build along so I see the templates your talking about and I'm definitely making a set of those.  That micarta sure is expensive. I may try some other plastic sheet goods as well. 

I stuck a 36 grit ceramic belt on and the groove was much deeper with that thicker belt, so i went back to the machine shop today and dropped off my drum and belt so that they can get a better sized rub collar for that combination. I'm also going to have it made out of 1/4 inch instead of 1/8 this time. 

I'm having a hard time coming up with a unique design for a longbow riser handle. I love the flared look, but there isn't a lot of room in the handle for that. My blanks are only 1.75 in deep. I may post some drawings on here to ask for your guys opinion. 060 for the accent strips is probably better than the 1/8 I was getting ready to use.

[Kirkll]

I cant imagine doing footed risers with 1.75" x 1.75" material.   My footed riser blocks are 3.5 - 4" wide.

i'll be interested to see what you come up with.