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Sanding inside the bowl

E

Edward Wargo

Joined
Mar 21, 2018
Messages
15
Likes
1
Location
Burlington, NJ
I am looking for a method that has proven to provide good results for sanding the inside of a bowl.
Tied to this quest is also a hunt for an electric 2" sander, or feedback on pneumatic sanders.
 
Have used several methods from hand to a pad to electric. Had an angled souix type drill till plastic bearings melted. Switched to a Pro Max angle drill and have used that for 3 years . It works well for bowls smaller that 4 inches and may be a challenge for deeper. Extension on a regular drill works well for bottom of hollow form. Getting into sanding hollow forms is a different story. I use mandrels from Turningwood.com made by Skilton and some I make myself. Have also found that since my cataract surgery I can see those scratches better and started using Abralon from the same source and really makes a difference in getting the last scratch.
By the way you will want to use a backup (orange) pad on your mandrel to protect hook and loop. Also do not skip grits when sanding work up from the grit you need to start at (usually 80 and some 120). When you see scratches remain go back at least 2-3 grits and rework that area. By doing that you may create a slight out of round but will not be visible.
 
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Edward I use Harbor freight angle drills and I usually make about a hundred bowls each year. I just get the inexpensive warranty on them in case of a lemon and over the years only one wore out early. Just blow them out after each use and they will do a great job at an inexpensive price.I only use the skilton sanding mandrels because they last 15 times as long as the cheap ones. 2" and 3" I tried the pneumatic sanders years ago but the high pitched whine hurt my ears after a short time using them. Also unless you have a very large air tank my compressor ran constantly when using them.
 
Edward Wargo said:
I am looking for a method that has proven to provide good results for sanding the inside of a bowl.
Tied to this quest is also a hunt for an electric 2" sander, or feedback on pneumatic sanders.
Click to expand...
I use an almost 20 year old Black and Decker drill that runs at about 2500 rpm. Tried right angle drill,and found no advantage. Balance did not seem right. Slow the lathe speed down to 4-500 rpm.I use a 2" Mandrell that I have rebuilt the pad several times and renew the Velcro loops by heating and peeling off and installing new which I buy in sheets and cut to size. Sand the inside walls at about 4 o'clock position with dust sucker right outside the edge of the bowl. Keep the pad moving all the time. On the outside, I sand in reverse with dust inlet high and behind bowl. Sometimes I reverse and resand with same grit. Start as low as you have to with grit and progress 60,80,100,120,150,180,220 or 240, 320 and 400. Sometimes go to 600 and 800. Sand serious tearout carefully with lathe stopped. I punch my own disks from cloth backed sheets with a sharpened plumbing union and a hand sledge on a piece of Brazilian flooring.
 
I think that the answer depends on a number of factors and there isn't a solution that fits everybody's needs. I do some hand sanding on the lathe and keep the sandpaper rapidly moving in a somewhat random fashion while paying careful attention to the the flow of the surface curve using my fingers to "see" the shape and also feel the thickness. The thickness doesn't have to be perfectly uniform,but there ought not be any sudden changes. I do my final sanding off the lathe. My method doesn't include anything out of the ordinary ... just a lot of elbow grease.
 
I use a Dewalt regular 3/8" variable speed drill. I used up several black and deckers before changing to the Dewalt (which is odd since they are the same company). I use 2 hands to hold the drill so it's really never been a problem. I find the angled drills too large for my hands and just don't like using them.
I use the 2" discs from Vince's woodnwonders and purchased a mandrel and backing pad for each grit. Since I started doing that my velcro last forever. When I just had one mandrel and had to change it each grit is wore out really fast.
 
I think Mikes statement bears repeating;
Mike Brazeau said:
Sand serious tearout carefully with lathe stopped
Click to expand...
With the lathe stopped, I sand the tear out till gone, and feather in (or out) the surrounding wood. Then power sand with the lathe running.
For taking a finish to the Nth degree I go to hand sanding. Sanding takes time, so minimizing tear out is an obvious priority, I sometimes think that all my cuts leading up to the last cut are practice cuts, if the tool, the wood and the stars align and the cut is good without tear out then I'm home free... If I'm getting tear out, I know long before I get to the final cut and take measures to minimize tear out, the first being to check the chuck, the second to sharpen, then it's just whats next in the bag of tricks, and sometimes, nothing works but the 80 grit skew... Well, 120 maybe...
 
Well, lots to think about here. The outside of a bowl is easier to turn and sand than the inside. I am becoming a big fan of NRSs (negative rake scrapers). They often leave a better surface than gouges, but a lot of that can depend on the wood. You want to do as good of a job off the tool as possible so you have less sanding to do. Dry wood will be much cleaner for finish cuts with the NRS than green wood. I just turned a couple, and the dry myrtle wood, I could probably start sanding at 220 or 320, but the green stuff would need 120. Part of that is because this myrtle, for reasons unknown, is leaving more tear out than any I have turned before, and I have been through a number of logs of it.

Abrasives work better at slower speeds rather than max rpm. Like dragsters burning off their tires, lots of smoke but they are going nowhere because they are slipping and not gripping. It is a traction thing... Since my bowls are all warped (green to final thickness, dry, sand and finish) I have my lathe rpm at about 20, and the drill rpm at 200 to 600 max. Coarser grits can go a bit faster than finer grits. I use a firm pad for grits up to 180 or 220. medium pad up to 400, and if I go over 400, I use the soft pads. The open abrasives like Abranet don't cut as fast as solid grits up to the 220 range or so, but then performance seems to be pretty close, though I don't use them much. Pretty much the same thing with ROS (random orbit sanders). Both are better for finish work and not coarse work. Oh, don't push the sander into the wood, kind of like rubbing the bevel, (the bevel should rub the wood, but the wood should not know it). Just the weight of the drill is fine. If you are pushing, then you are generating heat and wearing out your drill faster.

I have used the angle drills forever it seems, though I think the old style pistol grip drills may be a bit tougher. Pneumatic drills keep the compressor running non stop.

Still experimenting with NRSs. I have them from 80/30 trough 30/30. Current favorite is 45/30 which takes an excellent burnished burr. No conclusive opinions yet other than dry wood will respond better than wet wood.... I will have them at the Symposium if you want to come by my booth and play...

robo hippy
 
Gonna try again to finish what I was saying before I inadvertently sent the last post.
One of the issues I notice most often in my work is the fine lines that circle the bowl in certain areas and don't become evident until I apply the sanding sealer. I know there is not a one size fits all answer to any problem just as each of you that responded to the "Sanding the inside of a bowl", all have a different approach to sanding in general. I must be missing something right from the start of the sanding operation and may need to spend more time with the heavier grits.
 
Are the fine lines from sanding or from tool work? I've found that I need better lighting then I used to, and higher magnification. Some here have said to take the piece out into sun light, as the Sun reveals all...
 
I believe those lines are tool marks that were not sanded out with the coarse grits, The biggest mistake most make in the earlier years of sanding bowls and stuff is to stop with the coarse grit as soon as you don't see the tool marks or tear out any more. Then as you proceed to use the other grits when you get to the end those lines show up. 2 pieces of advice, get better light over your lathe, and keep sanding a little longer with the coarse grits before moving on, you will not regret it. I found that once you have a little finish on a piece the way light hits your piece allows us to see the surface differently.
 
Breck Whitworth said:
I believe those lines are tool marks that were not sanded out with the coarse grits, The biggest mistake most make in the earlier years of sanding bowls and stuff is to stop with the coarse grit as soon as you don't see the tool marks or tear out any more. Then as you proceed to use the other grits when you get to the end those lines show up. 2 pieces of advice, get better light over your lathe, and keep sanding a little longer with the coarse grits before moving on, you will not regret it. I found that once you have a little finish on a piece the way light hits your piece allows us to see the surface differently.
Click to expand...

Excellent advice. I don't recall if anybody mentioned it, but all sanding done after the coarsest grit is only to remove scratches made by the previous grit. If you discover tool marks somewhere along the way of using finer grits, you will need to back up to the beginning and take care of them before proceeding. Therefore, it's best to take Breck's advice and get 'er done right the first time.
 
I find that my Grex pneumatic sander with a 2 or 3 inch pad is the fastest, easiest, and most productive way to sand a bowl. I can start with 120 or 220 grit and work my up to 400 or finer (2000 is as far as I go in almost all instances) in a few minutes.
 
Hey, I can certainly relate to the more light and higher magnification agenda.
I have been hand sanding so to speak, I'm just holding a piece of sandpaper in my hand while turning 450 RPM. Based on your feedback, I'm going to spend more time with the coarser grits, while continuing to work toward achieving a better finish with my tool work.
Has anyone tried the Arbortech Contour Sander or the Merlin2 Mini Grinder?
 
Most of the time you can sand out tear out. Most of the time, you can not sand out tool marks.... Well bruises for sure...

robo hippy
 
Just read a piece by Flexner in Popular Woodworking on using sandpaper. Basicallly something we all know just delay doing. We should always use sharp sandpaper as it will cut the grain and using old paper makes the grain lay down and therefore raises it when finish is applied. https://www.popularwoodworking.com/jun18/grain-raising
This is a pretty good read
 
Mike Brazeau said:
I use an almost 20 year old Black and Decker drill that runs at about 2500 rpm. Tried right angle drill,and found no advantage. Balance did not seem right. Slow the lathe speed down to 4-500 rpm.I use a 2" Mandrell that I have rebuilt the pad several times and renew the Velcro loops by heating and peeling off and installing new which I buy in sheets and cut to size. Sand the inside walls at about 4 o'clock position with dust sucker right outside the edge of the bowl. Keep the pad moving all the time. On the outside, I sand in reverse with dust inlet high and behind bowl. Sometimes I reverse and resand with same grit. Start as low as you have to with grit and progress 60,80,100,120,150,180,220 or 240, 320 and 400. Sometimes go to 600 and 800. Sand serious tearout carefully with lathe stopped. I punch my own disks from cloth backed sheets with a sharpened plumbing union and a hand sledge on a piece of Brazilian flooring.
Click to expand...
Where do you get you’re cloth back sheets?
 
I buy them from http://sandpaper.ca/hook-and-loop-products/page-2/ when they are at our local woodshows. I believe they have a $50 minimum on line They recently bought the company from the people who started it years ago. I would call them rather than trying to order online as they assemle the combinations and see if they would put an assortment together. At our last Hamilton Wood Show they had 9x11 sheets I think 8 for $10 but I was able buy just a couple of sheets. They also have belts and disks etc so maybe you can get to the $50 with ease? I label grit on back of disks and put punched out disks in small baggies and keep in an old 51/4" floppy disk holder. Here is a quick iPad shot of my stuff. Edit - Just tried the link and getting an account suspended message for a couple of their links. Definiteley suggest telephoning.
 

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