Low speed drill for power sanding, sanding problems

[Justin Stephen]

Hello all. I feel like I am having some real issues sanding bowls that hopefully someone can suggest some solutions to. I am power sanding using a regular old Craftsman hand drill (tried one of the HF close quarters drill and did not like how it felt in my hand) most recently using Vince's stuff from 80-400.

On some recent bowls in particular (maple, probably sugar maple), I am getting abrasive streaks on the surface, especially after sanding with the finer grits. The streaks end up being whiter than the surrounding wood. The streaking is also more prominent on the outside of the bowl. Unfortunately, after a few coats of finish, I think some of these streaks are being highlighted by the finishing process.

My best guess is that I am sanding at too high of a speed with the drill and baking the surface of the wood from sanding heat. The areas around the streaks are suffering from surface hardening maybe? That would presumably be from the drill rather than the lathe since I am running the lathe at the slowest speed I can when I sand.

I also tend to get crease lines and even some pitting on the inside of the bowls on the sides. I tend to turn bowls with somewhat steep sides so far and I often get a crease line right where the side meets the bottom which the sanding is creating. It looks like the soft pad underneath the sanding disc is contorting itself into that curve well when I sand but I often get a difficult to remove crease anyway.

The problem with that is that the drill I have has too touchy of a trigger and it is very difficult to lightly depress it to keep the RPMs down at a low level. I would much rather have a drill that either had a trigger that was easy to depress and hold lightly or one that I could lock in at a very low speed, say 150-200 RPM.

I did buy one of those Sorby inertia sanders but haven't found a way to use it on the inside of bowls yet that I am comfortable with.

If anyone can help me diagnose/confirm the causes of my problems and/or suggest a different drill that meets my needs I would greatly appreciate it.

[Cathy Schaewe]

For that "crease" problem on the transition from the sides to the bottom, I have found that Vince's siasoft abrasive works very well. I just cut it into a small square or rectangle, turn the lathe on low, and hold it to the area. It conforms to the curve beautifully.

[Scott Hackler]

A couple things come to mind for your situation. First off I would say that you may be over sanding with the finer grits causing burnishing marks. Also, if you are working up through the grits keep a few things in mind, first dont start with 80... if you dont need to.. Meaning if the tool marks are barely there I wouldnt start out with anything heavier than 120. Any over aggresive grits will and often do, act like a shapping tool and will remove wood very quickly. The purpose of sand paper is to remove the sanding marks of the previous grits. If you are cutting your own sanding pads, cut them oversized and scallop the edge in a wave pattern. This will help around edges and keep the sanding pad from causing groves.

I maybe unique, but I sand very often at high speeds. Full throttle on the right angle drill/sanding pad set up and usually at the same turning speed. I am very used to this technique and only make one pass, back and forth before pulling the sander off the wood to stop heat buildup. I then blow off the piece completely with the air hose between every grit and I sand each grit using both forward and reverse on the lathe.

If your sanding at low lathe speeds, I would definitely be sanding with the drill at full throttle.
A regular shaped bowl is completely sanded and ready for finish in 10 mintues or so, doing this.

Now I understand that safety and heat issues are VERY GOOD reasons to slow the lathe down, but unless i am sanding irregular, NE or warped wood I go full speed ahead!

[Mark Hubl]

Couple of things. Sounds like your pitting on the inside may be tear out. Because of the nature of the grain change tearout is sometimes inevitable in different woods. When the spot is nasty to sand one of fellas in our club wet sands with the finish he will use. Sometimes lacquer, sometimes shellac. The finish stiffens the fibers and the slurry helps fill the spot. Not always doable but a good trick. It sounds like your transitional crease may be from your tool not your sanding. You may be riding the bevel a bit heavy at this difficult spot inside the bowl. This will burnish the wood. Once burnished it is difficult to sand out because that little section is now physically different from the adjacent wood.

I find maple can be difficult to sand because of it's tight grain, hardness and color. On the outside of pieces I usually turn off the lathe and drill and hand sand perpendicular to the lines the drill is creating. I do this with all grits. You don't have to hand sand much, just enough to help break up the lines. Maple being hard will really hold a line cut by the grit. Sometimes you will need to drop back a grit and be gentle then continue on. I like to wet the piece with alcohol or mineral spirits to pop the sanding marks. This really helps to see the stuff that is going to show up when finishing. Once these dry you can sand some more.

Unfortunately, I have found that drills with nice sensitive triggers are the spendy models. I just use the HF cheap o with Vince's stuff.

I will fess up here also, I usually sand at pretty high speed. If a piece is being difficult I will slow every thing down. The biggest problem I have with speed is that the sand paper bounces, don't laugh. Slowing things down lets the paper do it's best work. Sanding is like turning, you get better at it. Kind of a combo thing the better you are at turning the less sanding you will need to do. But, sanding is still sanding, not really loved by many.

[David Christopher]

Justin, I also sand like Scott.....I have my lathe turning fast and I power sand with a air die grinder....maybe you are sanding to slow and with too coarse of grit to start with

[Kyle Iwamoto]

I picked up a cheap Ryobi drill from the BORG. If you want to upgrade your drill. It seems to spin slowly enough for me. I used to use my Crapsman cordless, which I think has really excellent low speed control, but swapping batteries was getting old. I sand a LOT since I suck at turning. I use Vinces stuff too. That SIA paper is pretty good. For the finer stuff, after a couple passes with the drill, I usually finish off by hand, trying to follow the grain. Yeah, that's tough on the inside....

[Justin Stephen]

Thanks for the rapid replies, all.

It's funny that so many of you sand at such high speed. I certainly cannot contradict the validity of your methods from my years of hard-earned woodworking wisdom since...I don't have years of hard-earned woodworking wisdom. It does differ, however, from advice I have read in a few different places. One that springs immediately to mind is Russ Fairfield's "Five Rules of Sanding":

http://www.woodcentral.com/russ/finish2.shtml

[Justin Stephen]

Couple of things. Sounds like your pitting on the inside may be tear out. Because of the nature of the grain change tearout is sometimes inevitable in different woods. When the spot is nasty to sand one of fellas in our club wet sands with the finish he will use. Sometimes lacquer, sometimes shellac. The finish stiffens the fibers and the slurry helps fill the spot. Not always doable but a good trick. It sounds like your transitional crease may be from your tool not your sanding. You may be riding the bevel a bit heavy at this difficult spot inside the bowl. This will burnish the wood. Once burnished it is difficult to sand out because that little section is now physically different from the adjacent wood.

I was going to start using a product like Deft's or Minwax's sanding sealer on future turnings. Hopefully that will have some of the effect you describe above.

From both look and feel, I think I am creating at least a decent curve at that transition point on the inside of the bowl before I "call it good." I usually end up finishing that transition with a light touch rounded scraper.

[Mark Hubl]

It's funny that so many of you sand at such high speed. It does differ, however, from advice I have read in a few different places. One that springs immediately to mind is Russ Fairfield's "Five Rules of Sanding":

Guilty as charged, your honor. I would agree with Russ's methods. I admit to being lazy and not slowing my lathe down often enough when sanding. But like Bill Murray said in Stripes "Come on who didn't cry at the end of old yeller? Raise your hands."

[Scott Hackler]

Thanks for the rapid replies, all.

It's funny that so many of you sand at such high speed. I certainly cannot contradict the validity of your methods from my years of hard-earned woodworking wisdom since...I don't have years of hard-earned woodworking wisdom. It does differ, however, from advice I have read in a few different places. One that springs immediately to mind is Russ Fairfield's "Five Rules of Sanding":

http://www.woodcentral.com/russ/finish2.shtml

Justin, this topic will produce just as many "I sand slow" as "I sand turbo". It has a lot to do with comfort level and experience. I am not saying that I dont go slow...every now and then. Expecially for woods that are hyper sensitive to cracking from heat. But for the most part I taught myself to sand as high speed and know the limitations of the wood to heat ratio...I guess. One thing that works in my advantage, I believe, is that I am not sanding one little area of the bowl with the sander, causing the heat. I am also spinning that bowl at the same time and constantly moving the sander to prevent the heat, with breaks inbetween passes.

So for starting out (and maybe forever) I would suggest the tips you've received and low speed on the lathe, until you feel like you want to sand at a faster lathe speed.

[Mark Hubl]

I was going to start using a product like Deft's or Minwax's sanding sealer on future turnings. Hopefully that will have some of the effect you describe above.

From both look and feel, I think I am creating at least a decent curve at that transition point on the inside of the bowl before I "call it good." I usually end up finishing that transition with a light touch rounded scraper.

If your "crease" is not a burnish is it just a transition? Going from side to bottom you may be changing grain orientation. If the curve is too tight for the pad to fit into on the drill you may have to hand sand. I use the pad off the drill alot. Power sanding definetly is great, but it doesn't get into all my knooks and crannies.

[Justin Stephen]

If your "crease" is not a burnish is it just a transition? Going from side to bottom you may be changing grain orientation. If the curve is too tight for the pad to fit into on the drill you may have to hand sand. I use the pad off the drill alot. Power sanding definetly is great, but it doesn't get into all my knooks and crannies.

Pretty much. My problem is that I only remember to try and hand sand that area after I have created the crease and the crease can be a real bear to remove once created. I have had to revert to 80 grit (and therefore start over on the inside of the bowl) to remove it on more than one occasion. I have also managed to create creases closer to the rim (well away from the transition) as well though and I'm still not entirely sure how I am doing that.

[Ted Calver]

Justin,
I use both a HF and a Milwaukee close quarter drills and get equal performance. In fact I've had them both the same amount of time and the Milwaukee's bearings are about to go on me. The HF just keeps chugging. To help control the speed on the milwaukee I attached a piece of 1/2" thick +/- computer pad behind the trigger with double sticky tape. It keeps the trigger from being depressed any further than slow speed. I sand with the lathe at 100 rpms and the drill also going slow--it works for me. If you sand at high speeds and don't use restraint be prepared to buy a lot of velcro pads because the heat will melt them.

[Mark Levitski]

Justin,

Try sanding with the grain. This is one of the golden rules of finish sanding for flat work, but is very useful for turning too. Naturally, with facegrain bowls, the grain direction changes around the bowl. Power sand on the lathe but lightly and w/o it spinning, using the edge of your sanding pad going parallel with the grain. This means that you would be constantly changing the approach of the sanding pad edge to match the grain. If you, for instance, sand by merely holding the pad against the piece as it spins on the lathe, then you will alternately be sanding with the grain, against the grain, with the grain, etc. Those lines will especially show up against the grain.

I usually sand this way for the coarser grits, making sure with the current grit I leave no obvious lines form the previous one. Sometimes this means stopping the lathe and power sanding with the grain until you disappear the coarser lines.

Your lnes that show up in the finer grits are nothing but what you missed in the coarser. The fine grits are great for showing those up. You just need to go back and start again.

Yes, it's true that tool marks also play a role. Keep the effort up to get better with the tools and sanding will be a lot easier.

I will recommend the newer style Milwaukee close quarters drill. The other one where you can glue a stop pad behind the trigger (that includes the similar Sioux model) is not worth the money if you use it a lot--it'll wear out quickly.

Mark

[Scott Crumpton]

I sand both fast and slow, it just depends on what's needed for the particular problem. For example, on a natural edge item where I'll be sanding over air I turn up the speed of both the lathe and the drill and use a very light touch. Sounds scary, but it allows the gap to pass under the sandpaper without it moving into the air space.

Another thing I found is that it's imperative to sand with the trailing edge of the disc and (almost) never allow any part of the disk forward of center to touch the bowl. The only exception to that rule is the bottom of a flat bottom bowl.

In the transition area, I use only the very edge of the sanding disc, allowing the edge to conform to the curve of the bowl. This often requires holding the disc/drill at some rather odd angles. Also, keep it moving from center to edge and back again changing the angle of contact as you cross the transition area.

I generally keep the disc contact point rotating toward the edge of the bowl to avoid catching the edge, but will often make a light reversed pass to crisscross the sanding scratches.