Spindle sanders

[Don Case]

I am contemplating buying a spindle/ oscillating drum sander. I was a bit dismayed by the price. I'm pretty sure I could bodge one together for just a few bucks but it wouldn't have the up and down motion. Is that motion just to even the wear on the drum or does it contribute to the finish? I could put spacers or something in it if it's just to even out the wear.

[Mark P]

Good Evening Don;

 

The oscillation of the bobbin does improve the finish, as it avoids any chance of leaving visible parallel lines in your finished wood (this also depends upon the grit size of the abrasive you are using, of course)

 

All the best,

 

Mark P

[Jaager]

Don,

I did "bodge one together"  but it cost a lot more than "just a few bucks". 

The oscillation action was one that I could see no advantage in having and it provided the potential addition of a lot of precision problems with the up/down motion.

.

My primary use for it is to shape bevels on frames.

A deck beam or stem needs a precise 90 degree to the medium working surface.  Here, an accurate table is important.

For frames, a table just gets in the way.

 

I do not like using sanding sleeves.  The medium is expensive. The vendors are limited, so too is the choice of grit.  I do not trust the method that holds them.  Compression of a hard rubber rod can produce an out of round cutting surface.

I found a series of sleeveless sanding drums.  The largest diameter is 3",  but this size comes 3" tall and 6" tall.  (4.5" is pointless) .  There are others with smaller diameters - also 3" tall.  There is a shorter one with 1/2" diameter and if the rubber backing is removed, it is 1/4". (Inside curves)

For fresh cutting surface, I move the work, not the sanding surface. 

 

I built my first one using a seriously under powered motor that had on hand.  It did not perform all that well, but I learned several things not to do.

 

Things I learned:

A 1/3 HP motor does the job, but any less power probably will not. 

A 1/2HP would meet any challenge.  However, it is large, heavy, and significantly more expensive.  (I was able to suppress my inner Tim Allen on this point.)

This is where the expense comes in.

TEFC, CW/CCW,  a drum switch to reverse the rotation. A quality motor may well cost more than an economy spindle sander.

What makes it worth the additional expense:

The motor will have a 1/2" straight shaft.  Adapters and chucks are easy to fit.  Any cutter, burr, grinder, microplane, heavy duty flex shaft that has a round mount can be used with it. Being able to reverse the cutting direction is very useful.  (I discovered that heavy duty flex shafts do not like to have their rotation reversed - from reading the lit, not burnout.)

The commercial spindle sanders that I have investigated all use compression fit sleeves and the mount to the motor shaft is proprietary so no third party cutters will fit.  The belt sander option is neat,  but I bought a HF 3x36 dedicated belt sander for ~$50 with the 20% coupon. 

 

The process generates an unbelievable volume of dust.  To save burning out the motor from wood flour in the windings I use a TEFC motor.

Enclosing the motor in a box is a bad idea.  The heat needs to get away from the motor.  Two sides to hold the table. Two side open.

Bottom plywood plate that mounts the motor has a big hole that is the diameter of the motor.

I have a sheet of fiber board, with a 1/2" hole in the center just above the motor.  It blocks sawdust from getting to the motor.

 

A big drill press will hold the sanding drum, but I am tall and the motor blocks my view, so a motor on the bottom is necessary.

A good sight line is important.  Lots of light is important.  A way to hold the intake nozzle port for a powerful shop vac in a dependable fixed position is necessary.  A cyclone trap between the vac and the nozzle is necessary unless you like clearing or replacing Vac filters frequently.

 

[Don Case]

What kind of RPM am I looking for? Hopefully it doesn't want variable speed for different sized drums. I usually have an assortment of motors on hand but I don't at the moment. Once i get a plan in mind I'll head to the pawn shop and see what I can modify. At the moment I'm using a drum in the drill press but it's a pain to have to tear it down when I need to drill a hole.

[Jaager]

1700 rpm  - no RPM adjustment - faster than this burns the wood.

If this is for an occasional use, you may get by with an economy quality motor, but for serious work, going cheap may prove to be more expensive.

 

Big box home improvement stores have large size Erector Set type steel and bolts. 

These can hold the motor vertical and along with and "T" nuts, attach 3/4" plywood sides to the base.  Easier to undo, or adjust - glue is not a friend for this.

They also have free samples for Armstrong lino that can be cut and used as sound dampening "washers"  and large rubber bottle stoppers for feet to block vibrations and elevate to allow for air flow from below.

[Don Case]

I went to the pawn shop today and scored. for $10 I got a 1/4hp 1725rpm motor that someone had made a grinder with. It runs nice, came with a mount and I believe I can use the adapter that was holding the grinding stone on to the shaft. There has to be a name for that thing. When I made the drum for my thickness sander I bored a hole in a piece of 4x4, epoxied the shaft in and turned it down to 3" on my metal lathe. Then I glued the drum on. I have to peel the drum off and true up the surface when I need a new drum but it's not a lot of work. I've found that the drums wear like iron. I'll do much the same with this one.

[Jaager]

My old thickness sander was two pieces of Hard Maple with a 1/2" shaft bonded in the middle and the wood turned using the shaft as the chuck attachment.

 

For a drum sander table,  the actual drums?   It may be worth your time to visit the Peachtree Woodworking site and think about their sleeveless drums

I suggest the minimum  if you work at a larger scale  3 x 6"  3 x 2"  3 x 1"  3 x 3/4"    The core of the  3 x 3/4" is steel, so if the rubber pad is removed an even smaller drum is possible.

 

The Norton 10X sandpaper holds up, and unlike your thickness sander drum, the medium is held by a mechanical attachment.  The 10X has a non skid backing that rejects rubber cement and probably contact cement.  The thickness sander wants Klingspor cloth backed media anyway.

Edited February 2, 2021 by Jaager

[Don Case]

Those sleeveless drums look cool but wouldn't they have a noticeable "thump" every time you went past the seam? They're also kind of pricey especially with duty, shipping and exchange. Moot point as they don't have any at the moment

[Justin P.]

I put together a very effective setup with no oscillation using a drill press and table.   Speed is variable so easy to keep in the right area to prevent burn.  120 grit or above leaves a nice finish on hardwood (to be finish sanded at the final stage by hand). The whole setup out the door cost me less than $200 and I now have a drill press.   As previously mentioned the compression drums do get out of wack above about 1.5" diameter and no amount of centering seems to help.   If the drum stays under 1.5" Ive had no problems at all.   Adding a tilt to the table shouldn't be too hard with some thought put into the construction of the insert.   

 

I clamp a vac hose close up and all the dust gets sucked away during heavy use.   

 

[Don Case]

Nice. You guys do better work than me🙂 I tend to stop as soon as it works. My drill press chuck is just held in by the Morse taper and any vibration in the drum cause it to drop out. Here's mine. It sands square which is the big thing I guess. When I first put the drum on it was almost perfect, No wobble. I removed the drum and put it back on and now I have a very slight wobble. I found that if I have a very nice fit between the sanding tube and the drum that I don't have to glue it but that may only work with this tube. Now I have to come up with an easy way of raising and lowering the deck so I can use the whole sandpaper surface. That and dust extraction. Right now there is no back on it so it can cool. If I cover the back and always have the dust extraction on do you think there would be enough air flow to cool the motor? Also with the whole think closed up it would mean that the motor would be operating in a very dust environment. Fire or explosion hazard maybe. I don't know how sparky these motors are.

Edited February 2, 2021 by Don Case

[Jaager]

2 hours ago, Justin P. said:

Adding a tilt to the table shouldn't be too hard with some thought put into the construction of the insert.   

 

I clamp a vac hose close up and all the dust gets sucked away during heavy use. 

 

I have no insight into what jobs a drum sander would be help for with POB scratch.   My guess is that most of it involves a square angle.  It would probably do way more harm than good if used to bevel standard moulds.  For POF frames, the bevel is never a constant angle, it must be done by eye, so a tilt serves no purpose.

 

The dust generated by a sanding drum is a really significant volume of fine air borne particles.  Dust extraction is necessary.  It has a horizontal angular momentum of some velocity so if a shop vac nozzle is close the dust goes there rather than falling into the box with the motor.

 

29 minutes ago, Don Case said:

Right now there is no back on it so it can cool. If I cover the back and always have the dust extraction on do you think there would be enough air flow to cool the motor? Also with the whole think closed up it would mean that the motor would be operating in a very dust environment. Fire or explosion hazard maybe. I don't know how sparky these motors are.

 

My guess is that the motor is an induction motor.  The cooling of the windings is by convection and there is a grill of sorts at either end of the housing.   Saw dust will tend to pack around the windings and the motor will overheat.  I have never seen a brush motor that is as large as 1/3 HP.  The presence of sparking: only if there is a short in the windings?   The motor will get hot, but paper ~= wood  - it ignites at 415 F ?  I would think that the motor would fry and freeze up well before that temp was reached.

 

My prediction about your construct:  a closed back will make the box into an oven after a relatively short working time.  With just the back open, the working time will be a bit longer, but it will get hot -not enough free air exchange. 

The solution is to remove the front panel.  I used 1.5 inch angle steel (with holes) to do what the front and back panels on your box do - hold the sides at a fixed width.  Cut a big hole in the bottom panel where the motor bracing attachment ain't.  Put 1.5 or larger rubber corks at each bottom corner. It reduces vibration noise and allows for air flow from below. 

Now that I think on it, 4 pieces of angle steel could replace the bottom panel.  Two outer ones to fix the sides in position and two in the middle to hold the motor.  With the corks holding it up, there would be optimal air flow from below.

 

Buy a piece of the 1/4" thick stuff that peg board is made of, just get the version with no holes.  Make its dimensions a push fit inside your box.  Drill a 1/2" hole where the motor shaft hits it.  File the hole a tad bit larger.  With a TEFC  motor, it can be sitting on the motor housing, with an open motor, some gap is necessary. This shield will keep saw dust from getting to the motor.

 

Free hand bevel sanding - remove the table.  You are going to wish that the sides were not so high above the motor.   They should be about level with the top of the motor.

The table need not be a flat plane board.  It can have "feet" to position it up/down that sit on the side boards.  

 

For dust collection -  first I reverted to my previous life and bought a lab ring stand  and finger clamps to hold a crevice tool at the dust generation site.  The stand does not weigh enough, the finger clamps are too weak.   I replaced it with something sturdy that works.

 

It needed a lino washer on the positioning bolt to hold it at the required angle.

 

About the sleeveless drums,  the backing pad is beveled at the slot - no bump.   They have a 1/2" socket with a set screw.  They come with a 1/2" post so that they can fit in a chuck.  The rod can be removed and the drum can fix directly on the 1/2" motor shaft.

[Don Case]

I like your dust collector😃 You could move that around as needed.

 

You make some good points. I will lower the top (that was already planned to expose more sandpaper). I like the divider idea, it solves a couple of concerns. I'll have to tear it down a bit but I've got not much to do while I'm waiting for Longridge to arrive. Thanks