Belt-sander Linisher

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Introduction: Belt-sander Linisher

I have a need to sand some concave surfaces. A bobbin sander is too small a radius, I want a big, slow radius, so I've built a rig to turn my belt sander into a concave Linisher and it works rather well!

Supplies

Belt sander (mine is a Bosch PBS 75A)

Abrasive roll (mine is Abranet P120)

Some MDF and plywood from the scrap box and a few nuts and bolts.

Step 1: Make the Curved Platen

Let's start with the curved platen. It's made up of three layers, with the centre layer having an M8 hole and a 9mm gap in it. Set it aside for the glue to cure.

Step 2: Find a Way of Mounting the Sander

Your sander may well be different to mine, but we have to find a way of holding it securely. Mine has a couple of M6 holes in the side, so I used them. I cut a piece of plywood to fit so that it cleared the dust port and the air vent. This bracket also has a cylinder nut for mounting.

Step 3: Make the Baseboard

The baseboard is nice and big, about 500x400mm and is held down on the bench with a couple of holdfasts. A notch is chopped into the back edge to take and upright mounting plate. This has a slot routed into it, using the "Dropping-On" technique. I have a YouTube video of that technique if you need it.

The mounting plate is glued in, nice and square.

Step 4: Mount the Sander

A Bristol lever through the back slot secures the mounting bracket, and thus the sander, to the mounting plate. A small spacer (the green MDF in the photo) lifts the sander off the baseboard to prevent it scouring a groove. I found that out the hard way...

Step 5: Shape and Mount the Platen

When the glue is fully cured, bandsaw the platen into a curve. Mine is flatter towards one end and rounder towards the other, giving me a range of radii, rather like French Curves. Two M8 nuts are embedded into the underside of the baseboard and the platen is mounted onto a pair of matching studs..

Step 6: Make the Belt

If you can find a ready-made belt of the required size, then great, but I could not, so I made my own. The abrasive has to go around both rollers of the machine and the platen, with an overlap of, say, 20mm for the glue. The ends were cut at 30 degrees or so. I discovered that the abrasive is in two layers, the mesh itself and the velcro-type backing. The latter can be removed with a combination of thinners and scraping. This makes the joint less bulky.

I used contact adhesive, for its flexibility, and clamped the joint up overnight to let it cure fully.

Step 7: Let's Go!

The belt must be installed so that the joint trails, rather than leads on the platen, and is tensioned using the adjustment afforded by the slot in the platen. I found that I had to have it quite tight to avoid it stalling. There is not as much traction provided by the drive roller as there would be normally, becuase the belt is in contact for only about 1/3 of the circumference rather than 1/2. So I have to take it easy.

By removing the platen entirely, I can use the setup for flat and convex surfaces too.

Please watch the video and if you have any questions I'll do my best to answer them.


Enjoy!

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    20 Comments

    0
    schreib
    schreib

    11 days ago

    The whole heart of this system is the belt but you don't give much attention to the details of how you made the splice, how you lengthened it, the exact adhesive, Velcro removal details, etc. I have in the past attempted to re-splice abrasive belts like this and they quickly broke. It would seem you need to buy an overly long belt and custom cut it for your jig needs. OR, buy a second belt and splice twice after cutting the 2nd to length. . .
    Great job Steve; it would be nice to hear these important details.

    0
    stevemaskery
    stevemaskery

    Reply 11 days ago

    Fair enough. The abrasive is Mirka Abranet, bought from AliExpress in 0.5m (I think) lengths. It might be 0.4m. I'm not in the workshop. Anyway, I needed two pieces. The splice is approx 30°. I soaked the end with celluslose thinners and scraped with an old chisel. Yhe velcro layer came off. When dry, I uses UHU contat adhesive to make the lap joint. About 5/8" overlap, I guess, maybe 20mm. Clamped it overnight. Contact adhesive is flexible in a way that epoxy is not. It has to be mounted so that the overlap trails, rather than leads, I thinkit would shred in seconds if I had it the wrong way round!

    0
    schreib
    schreib

    Reply 11 days ago

    Some fine points:
    guessing that by celluslose you really meant cellosolve acetate, correct?
    Why use that and not MEK or Xylol or whatever?
    As to leading the splice. . . not clear. The splice can appear to be "leading" whether it is moving forward on either side of the belt. Wouldn't it be easier to just say copy the arrow direction on the belt and make the 2nd splice parallel to the one that exists?
    So, you say you need TWO pieces. How do you "get" two? Do you use two normal size belts, and dissolve / de-construct the splice on each and then make a two new ones the length you desire? Or did you find one really long belt and cut it down allowing the use of only one splice?
    Many belts(3M for example) do not have this "velcro" layer. What then?
    Do you think the UHU brand contact adhesive is special or would you consider just ANY contact adhesive acceptable? It appears your splice is breaking so I am left wondering if this is the best choice.

    0
    stevemaskery
    stevemaskery

    Reply 10 days ago

    Cellulose thinners is a solvent used for cleaning up cellulose-based paints. I don't know what it's called where you live. It's what I had in the cupboard.
    There are no arrows on the sanding material. The exposed edge needs to trail. If it is forward, it only takes the tiniest catch to become history. I had two pieces, rather than a roll. So I had to make two joints. I used what I had availalbe, I'm not suggesting that it is the definitively best way to make your own sanding belts.
    Lots of vids on YT.

    0
    schreib
    schreib

    Reply 7 days ago

    I looked it up on web and the stuff known as cellulose thinners in UK is a mix of four different organic solvents: nasty stuff and highly volatile I see! attached MSDS for you. Good Luck.

    0
    Arsted
    Arsted

    Tip 10 days ago on Introduction

    Hi, nice project. If the built-in dust collection is not keeping up, might consider adding a shroud (simple, could even be taped together cardboard!) and hooking up a hose to a dust-collector with a fine filter. The very-fine dust from sanding is the most dangerous

    0
    stevemaskery
    stevemaskery

    Reply 10 days ago

    That would be a very good idea, especially if being used for an extended period of time.

    0
    oldpunk666
    oldpunk666

    11 days ago

    you can get graphite pads/sheets/rolls relatively cheap from certain suppliers, even amazon, to atatch to your wooden back surface, in order to decrease friction on the back of the sanding belt and dramatically increase the life of your belt!
    great build though. i LOVE custom jigs and rigs!!!

    0
    stevemaskery
    stevemaskery

    Reply 10 days ago

    Thank you, that could be useful, although this was once-only setup for a particular project.

    0
    socaltoolguy
    socaltoolguy

    11 days ago on Step 7

    Very well done. I have a question though. How did you arrive at the desired contour of your sanding "block"? I see it is "multi-contoured". Very interesting design.

    0
    stevemaskery
    stevemaskery

    Reply 10 days ago

    I dust eyeballed it :)

    0
    stevemaskery
    stevemaskery

    Reply 11 days ago

    Nothing sophisticated, I just eyballed it out and sanded it smooth.

    0
    drizztzak
    drizztzak

    11 days ago

    I love this!! As a budding woodworker it's nice to see other ways to increase the use of standard tools. I'll be using this for sure!

    0
    throbscottle
    throbscottle

    11 days ago

    I don't own a belt sander, but making a static one soon - this is a great attachment I can build for, from scratch, and would never have thought of!
    Also today I learnt a new word! Thanks ;)

    0
    LarryG7
    LarryG7

    Reply 11 days ago

    learned

    0
    LarryG7
    LarryG7

    11 days ago

    A couple of ideas. The paten doesn't have to be in line with the sander as you have it. if it is moved to a position to the right in your illustrations the sanding belt would wrap around the drive wheel to a greater extent. Maybe even mounting it in front thus substituting it for the front roller. I believe only the rear roller is powered.

    Second I believe I would choose a belt first and then put the paten where it needed to be. No need to glue a belt together. And I agree with others, it is not easy to glue the ends together and make it hold, especially without creating a bump.

    0
    charlessenf-gm
    charlessenf-gm

    11 days ago

    Ah, intercourse with necessity triumphs once again!

    I would join that rank of viewers anxious for details on the construction of your custom belts. Possibly including a link to the manufacturer of the materials you used and the belt material itself. We have Klingspor shops in the USA where one can purchase all manner of abrasive material in bulk as well as packages of material in 'regular' shapes and sizes. Problem is, there are as many different approaches to creating such materials as there are fingers remaining on your hands.

    Again, great project! Thanks for sharing!

    Then again, why not search your u-tube for:
    Homemade Sanding Belts
    Make Your Own Sanding Belt
    Making your own sanding belt - fast and easy
    Make Your Own Sanding Belts
    *** Make Your Own Sanding Belt Handmade Creative Channel
    HOW TO MAKE STRONG JOINT BELT GRINDER SANDPAPER

    0
    sharpstick
    sharpstick

    11 days ago

    The platen looks like mahogany. Did you treat it with any sealer or lube to keep friction from burning it?

    0
    stevemaskery
    stevemaskery

    Reply 11 days ago

    It's Douglas Fir, just sanded. I didn't lube it. Putting any sort of lubricant on it would reduce the traction from the drive roller even further. It doesn't get hot.

    0
    seamster
    seamster

    14 days ago

    Very clever! I love seeing projects like this. Very well done, thanks for sharing the idea and details! :D