Shopsmith Forums

Hi All,

I've made some bowls and lots of pens on the shopsmith, but I've never had this particular problem before. I'm using ambrosia maple, and I'm desperately trying to get a smooth surface prior to finishing.

It seems like no matter what I do, I get scratches in the wood from the sanding process, that I can't seem to remove with successive grits.

I'm starting my sanding process with a 150 grit disc on my power drill, while the lathe is spinning. This works fairly well, but occasionally the disc will catch and leave some deep scratches in the finish, so I then have to re-sand everything.

Once I get a decent 150 surface, I switch to 220 using a rubberized block, or just by hand. I've also tried using sanding "sponges." The 220 gets the majority of the 150 grit scratches out, but adds its own scratches, some quite deep. Switching to 320 doesn't seem to be able to remove these, as the paper gets loaded up so fast.

So, is this inherent to ambrosia maple? Is my technique bad? Should I be doing something differently?

Thanks for any advice.

-Chris

Chris, you should be able to get an excellent finish on ambrosia maple, which is simply soft maple that's been infested by the ambrosia beetle. I've not turned ambrosia maple, but have used it in other projects and obtained excellent results using a random orbit sander with 100 through 320 grits.

I think your problem may stem from the disks or rubberized sanding blocks you are using, in that their edges are digging in or gouging the wood. Those sanding disks used to sand bowls are typically soft and flexible, so if you're using something hard you may want to simply skip them and use hand-held sandpaper. As you step through the grits, use lighter and lighter pressure. Those sanding sponges should be O.K. as well. After sanding with 150 grit paper, you should have a smooth finish on the bowl with only scratches that are caused by the grit itself. These scratches should be removed by the 220 grit and whatever scratches are left should be removed completely using light pressure with the 320 grit.

are you sealing the wood before you sand? i use deft lacquer sanding sealer thinned 50-50 with lacquer thinner. it dries in minutes.

cml wrote:Hi All,

I've made some bowls and lots of pens on the shopsmith, but I've never had this particular problem before. I'm using ambrosia maple, and I'm desperately trying to get a smooth surface prior to finishing.

It seems like no matter what I do, I get scratches in the wood from the sanding process, that I can't seem to remove with successive grits.

I'm starting my sanding process with a 150 grit disc on my power drill, while the lathe is spinning. This works fairly well, but occasionally the disc will catch and leave some deep scratches in the finish, so I then have to re-sand everything.

Once I get a decent 150 surface, I switch to 220 using a rubberized block, or just by hand. I've also tried using sanding "sponges." The 220 gets the majority of the 150 grit scratches out, but adds its own scratches, some quite deep. Switching to 320 doesn't seem to be able to remove these, as the paper gets loaded up so fast.

So, is this inherent to ambrosia maple? Is my technique bad? Should I be doing something differently?

Thanks for any advice.

-Chris

Chris personally I would loose the power drill and sanding sponges. Start with 120 grit and work through 220 grit using sand paper and hand pressure and only. This should leave an excellent surface for a finish on soft maple.

I use a "Sorby" sanding disc, I got from woodcraft.
I use it with a Harbor Freight pnuematic angle grinder.
I,ve gotten great results with it.
http://www.woodcraft.com/catalog/produc ... rodid=9296

I use a "Sorby" sanding disc, I got from woodcraft.
I use it with a Harbor Freight pnuematic angle grinder.
I've gotten great results with it.
http://www.woodcraft.com/catalog/produc ... rodid=9296

if the above solutions don't fix your problem, you might try using compressed air to blow the grit out of the holes in the ambrosia. this would be to get rid of grains of the larger grit that can come out when you are sanding with the finer grit.

also, I don't know if the ambrosia is harder or softer than the rest of the maple. if edges of the holes are chipping off, then they might be the source of your problem. if so, then you may need to fill the holes with some thin CA or with your first coat of finish (if you are using a coating rather than an oil) to stabilize the material. the problem then becomes whether the hole filler will interfere with the color of the finish.

I am knot speaking here with any experience sanding ambrosia maple, so take my suggestion with a grain of salt, but what about trying steel wool?

I have turned a lot of bowls and have had great luck with the "new wave" sanding discs. I get them through Craft Supplies USA. They have a website and I order them on-line. I also use a right angle electric drill. Doesn't catch like the regular drill does. Much easier to control. I have also used a Sorby angle sander with great results. Also available through Craft Supplies USA.

The more bowls you make, the better they turn out. There are always a few mistakes that happen also. Have Fun!

Dean