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Thickness Sander from an 8 x 4 sheet of plywood

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Blog entry by Jim Rowe posted 517 days ago 2902 reads 16 times favorited 15 comments Add to Favorites Watch

This is my first attempt at blogging but I thought people might be interested in the approach I took.

Getting hold of consistently dimensioned timber for making boxes has always been a challenge, especially when small thicknesses are required and when the timber is hard to come by (expensive and scarce). I have seen many examples of beautiful boxes here on LJs from makers who have either made their own thickness sanders or have bought commercial equipment. For me, buying a ready made thicknesser is not an option (far too expensive) so I decided to make my own. There are many excellent examples here on LJs so I have taken ideas from many of them. Many thanks to all of those who went before.

I decided at the outset to use a 2440 X 1220 mm (8’ X 4’) sheet of exterior 12mm (½“) plywood instead of the “banana wood” available from our local DIY outlet (B&Q) for reasons of cost and the chance to avoid warping during construction. I also decided on a 380 mm (15”) bed width as I had access to some free 19 mm (¾“) ply that had a melamine laminate on both sides. Off cuts from the fitting out of van interiors. I used a friend’s table saw to rip the plywood into strips that were 90mm (3 ½”) wide and 900 mm (35”) long.

I decided to laminate 3 layers of ply using a combination of hide glue and Titebond to create the framework. It was fairly easy to create mortise and tenon joints with the 3 layers and lots of clamps. The end product is very rigid but still quite light.

I used pillow bearings to hold the 120mm (4¾”) drum made up from 19 mm (¾”) mdf discs on a 19 mm (¾”) steel shaft. The discs were glued to the shaft with a combination of epoxy and Titebond. The shaft was trued up to the infeed table using a sled with 80 grit paper attached. Sticky back Velcro was fixed to the drum and sandpaper attached to the Velcro.

I used a 1400 rpm 1.1Kw (1½ HP) electric motor which was initially left as self tensioning for the belt pulley but later was fixed down using a tensioner to reduce the vibration when in use.

The adjustment mechanism was made from 12 mm (½”) threaded rod held in a captive nut system. Can’t think of another way to describe it. The rod I used has 15 threads per inch, so one full revolution raises the table 1/15th of an inch or 67 thou or 1.67 mm in real money. The adjustment disc has 10 indentations or segments so one division is equal to 1/150 of an inch. A nylon nut holds the adjuster in position to avoid movement from vibration.

The dust collection hood includes 2½ “ rainwater piping and is connected to my dust extractor.

I fitted adjustable and lockable wheels to allow me to move it around my very cramped working space.
I reckon I spent about £250 on the build, less than half the price of a readymade job.
So far, it does what it is supposed to do which is to fine sand timber to a consistent predetermined thickness.
Just one word of caution – when adjusting the table height it should be done in very small increments, one or two divisions on my scale, to avoid blowing the sandpaper off the drum which can be a very scary experience!

Here’s the finished article. Hope that you might be inspired to make one for yourself. Any questions or comments are welcome. I didn’t use all of the plywood in this construction so I have some left for the next challenge!

-- It always looks better when it's finished!



15 comments so far

View smitdog's profile

smitdog

79 posts in 730 days


#1 posted 517 days ago

That sure looks nice, I need to build one of those! I’m loving the laminated plywood finger/mortise & tenon joints I’ve been seeing lately for building your own tools. Does your height adjustment just raise one side of the table and hinge on the other side? Seems like a fairly simple build, how many hours do you have in it?

View shipwright's profile

shipwright

4899 posts in 1423 days


#2 posted 517 days ago

Great build blog for a first try.
Gotta love the hot hide glue and I can vouch for the interlaid plywood joinery. It may come prettier but it doesn’t come any stronger than that.
Can you explain what you mean by “combination of hide glue and titebond” and “combination of epoxy and titebond”.

Thanks.

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/

View Jim Rowe's profile

Jim Rowe

547 posts in 937 days


#3 posted 517 days ago

Smitdog – The table is hinged at the rear, so the adjustment mechanism tilts it upwards. I didn’t keep a detailed check on the time but it must have taken between 25 and 30 hours all in. Worth every minute!
Paul – I made this over the winter in my unheated, sub zero, shop so I used hide glue when temperatures allowed ( I even borrowed the wife’s iron to heat some of the pieces to make things easier to assemble) and at other times I took pieces indoors and assembled them in a more convenient atmosphere. The joys of an English winter! I used epoxy to fix the mdf discs to the axle rod and joined the discs to one another using Titebond. Using epoxy throughout would have been an expensive challenge. I really prefer hide glue but it’s not always possible in all circumstances.

Jim

-- It always looks better when it's finished!

View jap's profile

jap

1225 posts in 679 days


#4 posted 517 days ago

good job

-- Joel

View ruddy's profile

ruddy

396 posts in 1564 days


#5 posted 517 days ago

Hi Jim,
I like the build and have to say I am just a little envious. I have often thought about building one of these and your blog is ideal. The finished unit is very simple and the plywood construction would be extremely strong and rigid. Thanks for posting a very informative blog.

-- And my head I'd be a scratchin'

View gfadvm's profile

gfadvm

10717 posts in 1315 days


#6 posted 517 days ago

Nice build! I have a lot of admiration for people who can build their own tools!

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View bluekingfisher's profile

bluekingfisher

1008 posts in 1604 days


#7 posted 517 days ago

Great job on the build and thanks for the translation from imperial to metric scale -;)

I’m sure you’ll have years of use from her. If you had to do it again what would you change?

David

-- No one plans to fail, they just, just fail to plan

View Jim Rowe's profile

Jim Rowe

547 posts in 937 days


#8 posted 517 days ago

David
Next time I would use better quality plywood, probably Baltic Birch, and I would definitely start the build in the summer to avoid the hypothermia and frost bite risk of the winter months!
Jim

-- It always looks better when it's finished!

View bluekingfisher's profile

bluekingfisher

1008 posts in 1604 days


#9 posted 516 days ago

Baltic Birch hard to beat Jim, as you are no doubt aware a little more costly but in the grand scheme of things not cost prohibative. Still, I’m sure the ply you have used will stand up to the rigours. The build quality can be faulted.

I concur on the seasonal build time, I haven’t ventured into the WS for a while, least not for woodworking other than to collect tools for the WC refit, even that has been a traumatic experience this winter.

-- No one plans to fail, they just, just fail to plan

View Sergio's profile

Sergio

402 posts in 1317 days


#10 posted 516 days ago

It is one of the best designs I hv seen, The lamination of plywood gets everything easier. My workbench is like that, no time, tools or expertise to make all the tenons needed, but in the end you get a very sturdy structure. Have fun with it !!!

-- - Greetings from Brazil - --

View lew's profile

lew

9991 posts in 2380 days


#11 posted 516 days ago

I like the belt tensioning idea. I get a lot of vibration on my sander because I left the motor hang to provide the weight for the tension.

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

View Johnnyblot's profile

Johnnyblot

318 posts in 901 days


#12 posted 516 days ago

Hi Jim. Well done.
I have looked into making one of these myself, but not got around to it :-(
I think one of these sanders would be great for accurately dimensioning stuff, for making boxes for instance.

A couple of points-
Where did you source your pillow bearings from?
If you used 12mm dia. Rod then, being metric the thread pitch will be 1.75mm . (12×1.75mm) This means every full revolution will move the table by 1.75mm. Half a rev will be 0.875mm, and so on.
Therefore to raise/lower the table 1inch (25.4mm) it will be:-
25.4 divided by 1.75= 14.51 revs
So 15tpi is not quite right.
I only mention this cos I was thinking of using a 6mm dia. rod, as the thread pitch is 1mm. (6×1.0mm). Which will hopefully make it easier to judge dimensions accurately.
Anyhow great sander. I may have to pick your brains when I get round to building one.

Cheers,
John.

-- Gossamer shavings just floating around the back yard….-Bandit

View Jim Rowe's profile

Jim Rowe

547 posts in 937 days


#13 posted 515 days ago

John
I found the pillow bearings on eBay. Search for Pillow Bearings and you will be spoiled for choice!
I used components from B&Q for the adjuster mechanism shown here in its disassembled state with a dome nut to give a smooth contact surface with the underside of the table.

The threaded rod was bought as “M12” which in fact turns out to be 11.4 mm in diameter

I counted 15 threads per inch

So that’s how I came to my calculations. At the end of the day I will use a dial caliper to check the thickness achieved and will creep up on the desired measurement in very small increments.
If you have access to accurately dimensioned threaded rod you will obviously use different calculations.
I think that 6mm rod might not give enough torsional strength for the table which is quite heavy (11/2 inches) and subject to quite a bit of vibration. Good luck!
Jim

-- It always looks better when it's finished!

View Johnnyblot's profile

Johnnyblot

318 posts in 901 days


#14 posted 515 days ago

Hi Jim
Thanks for that. I have some M12 threaded rod lying around so I’ll use that.
As the M12 is a nominal dia the pitch will still be 1.75mm.

I’m guessing the rod through the drum is 12mm too?
Did you get the abrasive paper from Axminster Tools??

If we ever get a summer I will see about building a sander :-)

Cheers
John

-- Gossamer shavings just floating around the back yard….-Bandit

View Jim Rowe's profile

Jim Rowe

547 posts in 937 days


#15 posted 514 days ago

Hi John
I can still only count 15 threads! Not to worry, it’s probably my eyes!! You just need to creep up very gradually on the thickness you are aiming for. Threads per inch don’t matter. If you are too aggressive with the amount of timber you want to take off in a single pass the sandpaper will “explode” off the drum – very noisy and expensive to replace.
The rod through the drum is 19mm from Mallard Metals http://www.mallardmetals.co.uk so you will need 19 mm pillow bearings.
The velcro backed sandpaper is on eBay, as is the sticky backed hooked stuff that you fix to the drum.
Sandpaper
http://www.ebay.co.uk/itm/290802937515?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
http://www.ebay.co.uk/itm/280626730702var=580016762654&ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
Velcro
http://www.ebay.co.uk/itm/VELCRO-SELF-ADHESIVE-STICKY-STRIP-1mtrsx100mm-LOOP-ONLY-/390556184663?pt=UK_Crafts_Sewing_Supplies_MJ&hash=item5aeef67057

More details about construction on the blog http://lumberjocks.com/JR45/blog/35168
Good luck!
Jim

-- It always looks better when it's finished!

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