Improving a Homemade Thickness Sander

[Roger Pellett]

Having finished up a number of non ship model projects I’m ready to get to work in the new year.  I have two boxwood planks that are begging to be used while I still have my wits about me, so I decided to build a “natural finish” model featuring this beautiful wood.  Before starting I decided to overhaul my Byrnes Saw and get a better thickness sander than my homemade one.

 

Before writing an order for a new sander I took a second look at my old one.

 

The more that I looked at it, the less inclined that I was to replace it.  

 

 

 

 

It’s a heavy duty floor mounted machine.  The need to glue the sanding medium on is a pain but cloth backed belt sander belts last a long time.  I also like the 12in did sanding disc mounted on the left side.  The main thing that I don’t like is the gymnastics involved with having to get around the back of the machine to pull work out while not letting go altogether and launching a missile.  While the Byrnes sander looks like an excellent machine, I decided that before buying one I would try to add a feeding mechanism to my homemade sander.  This would let me feed material in from the front without the need to pull it out of the back.  I also enjoy the satisfaction of using tools that I have built myself.

 

 

I have a simple crank operated feeding mechanism roughed out in my mind and intend to post progress as I go forward.

 

Roger

[Jaager]

Roger,

My question: how will you secure the wood stock to the constant feed?  I see a lip at the bottom as pushing it, but i suspect that the stock will want to cant and if the angle becomes a critical one, it will come flying back at you.

My bandsaw leaves an unsmooth surface on my stock.  I have to sand both sides. It takes several passes to get to spec.  Finding the sweet spot for bandsaw slice thickness is an ongoing challenge.

Thick enough that the final product is 220 smooth on both sides, but that not many extra passes at 80 grit are needed.  I flip and/or rotate my feed.  I do that as I get it thru the drum.  An auto feed I see as dropping over the back cliff. There is no way to do a proper flip/rotate. 

 

I use Best Test rubber cement to hold paper backed medium to my disk sander - double coat.  It holds well enough, is easy to peal off, and cleans just using my thumb.  The no skid backing on 10X Norton is chemically incompatible with rubber cement,  so big volume big box store stuff I cannot use.

 

I have a similar home made thickness sander.  It is a box and I made the mistake of enclosing the lower motor chamber - it becomes a right oven so I can't lock on and run for a long session.

I use cloth backed Klingspor  - long rolls - direct from the company.  But, I did not find the courage to try rubber cement for it.  I still used contact cement - double layer - it holds well enough - boy does it hold - I can use naphtha to clean it up, but it does not dissolve it, just denatures it and not all that quickly either.  I did break down and purchase a Byrnes machine.  The media is much easier to change. It does not overheat.  My old machine has clean media and is ready to go, but the Byrnes is so much easier that it staying in storage.

 

My suggestion - go with the Byrnes.

Alternative -  fix casters on your old units and pull it out into your shop floor and give the feed improvement experiment a pass.

 

Oh, the 12" disk sander will still be there.  I have a 10" on my old and retired 3 wheel Emco Meyer band saw, but I have never mounted it.  I also bought a disk that fits the arbor of my 10" tablesaw - an on sale thing - that makes it a disk sander - still in the box.  If my 5" Byrnes will not do it, the Harbor  Freight 4x36 belt sander will.

Edited January 9, 2021 by Jaager

[Gaetan Bordeleau]

9 hours ago, Jaager said:

My suggestion - go with the Byrnes.

Byrnes will not give better results; same principles, same results.

 

Thickness sander, milling machine and lathe need  an automatic feed to get a constant thickness.

Hand feed never gets constant thickness.

[Jaager]

2 hours ago, Gaetan Bordeleau said:

Thickness sander, milling machine and lathe need  an automatic feed to get a constant thickness.

Hand feed never gets constant thickness.

I am more than confident that what you say is true. 

 

In the lab, we had a rule on rinsing the soap off of just washed glassware. The first rinse removes 95%. The next rinse removes 95% of remaining 5%.  Each subsequent rinse does the same.  It will never be 100% removed.  Like we had to decide when we had done enough rinses, for precision on wood stock,  we need to decide when it is precise enough.  I would not be surprised if there was not a rule to the effect that the cost for each increment that increases precision: that much more,  has an inverse cost to the additional fraction towards absolute precision that it provides.  We need to decide for ourselves when close enough is good enough.  For me, a hand feed Byrnes machine is close enough.

[Roger Pellett]

Gaetan and Jaager,

 

Thanks for your advice and comments.  Howard Chapelle once wrote that ship model makers are stubborn cusses and it seems that I am one of them.  An unstated aspect of this project was to avoid cost by dipping into my extensive collection of scrap and junk.  So far the cost of this improvement is $7.25.  One of two things is going to happen; It will result in an improved machine or we’ll learn what won’t work. I have some ideas for safeguards to avoid getting material thrown back in my face.

 

Roger

Edited January 9, 2021 by Roger Pellett

[Jaager]

Roger,

I get a continuous/ daily stream of email  missives from these guys, but they do have some useful stuff=  Woodworkers's Supply.  I did a search for casters, and this product might could solve your mobility problem for ~ $40. 

https://woodworker.com/2-12-diameter-total-locking-casters-mssu-166-751.asp

 

 

[Gaetan Bordeleau]

When possible every machine has his own automatic feed. The surface grinder has his moving table. The  saw bench has the power feeder and so on.

 

I remember in the first years I was turning metal. For the last pass, automatic feed is use.  I remember that to fully understand the meaning of a nice finish, i looked at it to the microscope because we had a discussion about this subject. Somebody was saying that finishing by hand  was as good, until he saw a picture taken to the microscope. When turning precision diameter, automatic feed is always use because the diameter of the part will be more constant and it will be always easier to fit a part finished with the automatic feed.

[Roger Pellett]

Gaetan,

 

yes, I agree but I don’t want to spend over $1000 for a commercial model.  On the other hand, I never really got satisfactory results from my machine as it was.  It was necessary to push the stock in from one end, then without letting go, get around to the discharge end to pull it out.  In doing so it was impossible to maintain anything even close to a constant speed and in some cases the stock would shoot back at high speed.  In looking at the Byrnes machine, it seemed that I would have the same problem.  If my modifications work i’ll have a far more useful machine than I had before.

[Gaetan Bordeleau]

36 minutes ago, Roger Pellett said:

In looking at the Byrnes machine, it seemed that I would have the same problem.

I think so. As far as I know, it does not have automatic feed!  Also, your machine, by having a bigger motor can sand faster, so it means you can do the job faster than Byrnes machine.

[Roger Pellett]

Making progress:

 

The sled, glued up from several pieces of 3/4in T&G hard maple flooring.  The cross piece stop is a light press fit into a groove.  It is semi sacrificial.  

 

 

 

The rails in place.

 

 

Progress, Sunday evening.

[Roger Pellett]

A nasty day outside today so I got uninterrupted time in my workshop.  I got busy on the rope drive to feed wood into the sander.

 

 

First, I needed some pulleys.  These were made from aluminum angle iron from the scrap bin.  A pair of nice brass sheaves were scavenged from a pair of hardware store bought for a now forgotten project many years ago.  Miscellaneous machine screws, nuts and washers are from my parts drawers.  Net cost of all this:  $0.00.

 

 

Pulleys mounted on the machine’s back end.  Tomorrow, I’ll get busy on the front end.  This will be more complicated.

 

Roger

[Roger Pellett]

I spent the week making parts, now all finished except the 1/2 in steel shaft that has to be drilled to accept cotter pins.  I splurged and bought the four 12mm Id flanged collars about $20 delivered from Amazon.  I used two of them so have two left over for something else.  The 12mm bore was easily bored out on my drill press to fit a 1/2in shaft.  I should have it assembled in the next couple of days

 

 

 

the disc disc in the foreground is a rachet, a precaution to prevent the machine from eject the sled into the operator.  To back up the sled the pawl (not made yet) is disengaged.

 

 

The cardboard pattern for the ratchet.

 

[Roger Pellett]

The machine upgrade is finished and works well.  The piece to be sanded rides through the machine on a sled.  The hand wheel on the right hand side turns the drum on the shaft, winding the white cord to pull the sled through the machine.  The sled can accommodate wood up to 15in long.  This means that I can sand a 40 to 60 ft piece at the scales that I usually work to.  Kickback protection is provided by the ratchet and pawl on the left hand side of the machine.

 

 

 

Edited February 2, 2021 by Roger Pellett

[Don Case]

I like it😃 I'm a little afraid that a kickback would shear off the stop piece stop but I dunno. How do you get the sled back to the starting position?

[Roger Pellett]

In the event of a kickback, the ratchet rotates backwards, counterclockwise and the pawl engages the teeth stopping movement. The pawl is pinned at the top, so is in compression only; no shear or bending.  There is a spring that keeps the pawl in contact with the ratchet teeth.

 

To retract the sled, the machine is turned off, the pawl is rotated by hand counterclockwise to disengage, and the sled is pushed back by hand.

Edited February 2, 2021 by Roger Pellett

[Don Case]

The pawl stops the sled but that little strip that goes across the sled is all that stops the workpiece isn't it? Am I missing something. Have you got the grain vertical on that stop piece or something?

[Gaetan Bordeleau]

19 hours ago, Roger Pellett said:

The machine upgrade is finished and works well.

This is the first time I see a home made sander with an automatic feed by hand, very cleaver!

[Jaager]

Roger,

There is probably a bit more control, but a hand crank feed or direct push of the work into the rotating drum - still involves a human factor into the constancy of the rate of feed.

A motor driving the feed table would solve that.  I have never used one, or even seen one in operation, But does not a full size planer that uses cutting blades also have a motor driven feed?  I sure would not care to get my fingers near those rotating blades.  With a sanding planer, all I get is interesting fingernail tips.

[Roger Pellett]

Jaager,

I have one of the portable Dewalt planers that I have on a homemade stand.  I bought it to plane locally cut cedar for my canoe rebuilding projects.  It does have power feed, but when planing the hard model building woods the feed rate is not necessarily consistent because the lumber is not   Power feed is provided by one or more rubber coated rollers and these can slip when they hit a thicker spot.

 

 Although hand cranking may not be the ultimate, my system solved the problem that concerned me; the need to push  the wood into the front of the machine and then pull it from the back.  The results so far are much better.

 

Don,  you’re right, the strip across the sled is in shear.  The ratchet exists to keep a kickback from sending he sled into my face.  The little strip is a piece of tough hickory left over from another project.  As the machine gets more use, we’ll see how well it holds up.

 

Roger

Edited February 3, 2021 by Roger Pellett