Power sanding - why am I tearing up backup pads?

[Brian Kent]

I keep on tearing up the 2" yellow backup pads when power sanding. I am using Vince's pads on a Neiko angle drill. The lathe is on its slowest speed - 250 rpm. The angle drill is on 1/2 speed or even less. The back up pads usually break while I sand at lower grits.

At first I overheated some innerface pads and delaminated the velcro. I slowed way down and have not done that any more.

I may be putting too much of an angle on the edge of the sanding pads relative to the bowl surface. That distortion could be wearing out the foam. I also may be adding too much pressure towards the bowl surface and increasing torque.

As I look at Vinceswoodnwonders site it looks like he is using a new white latex foam for the 2" pad. Has anyone tried that?

Thanks all. I am trying to correct my technique because the results are terrific with this system.

Brian

[John Keeton]

Brian, first, my suggestion is to call Vince. Great guy, good products, and very willing to talk with you. That said, sandpaper does its work by moving an abrasive across the surface of the wood. Using too much pressure is a common mistake with sanding. Not only does it generate heat, which destroys pads, etc. and can cause degradation in the wood, it also is unnecessary and does not improve the end result. One usually ends up with deep scratch patterns that are difficult to remove.

Use light pressure and let the sandpaper do its thing. Clean and/or replace the sandpaper often. It is cheap compared to backup pads and a finished product.

Edit, I should add - talk with Vince about the different types of backup pads to use with each grit. There is a method to that system and his advice will be helpful. Using one backup pad thru all the grits is not usually the best answer.

[Ken Fitzgerald]

Brian,

I agree wholeheartedly with John. Use less pressure and allow the sandpaper to do its job. I agree with cleaning the sandpaper too.

[John M. Smith]

I also agree with John. Do not use too much pressure. It just overheats everything. Also, as you go up in grit number, you must heep adding interface pads. Ithink there are two other ones. But I cannot remember at which grit you add them. Call Vince. He is a great guy.

[Brian Kent]

Thanks, everybody. I did get ahold of Vince and got some good information. His recent batch of yellow backup pads has not been as durable s they have been for the last ten years. He has changed materials. He confirmed the light, slow sanding technique and said it may not be the fault of my technique. So I ordered a new white backup pad and a low profile backup pad. Vince likes the low profile since soft foam in that part is not as important as the innerface pads.

One important note - I have gotten adequate usage from the yellow pads, but they were the point of failure in my work. I am not disappointed in the product - just trying to do it right and happy that there is an improved product available.

[Jack Gaskins]

Too much TORQUE and PRESSURE. I have had several pads twist right off. All you need to do is epoxy them back on. I haven't had anymore issues after using epoxy. You would think that the bonding agent on those yellow pads would be better for $8 a piece. Packard Woodworks sells a black foamed holder for $15 but it is pushed as a heavy duty holder. Sanding Glove also sells a heavy duty hold that looks like it would last forever but they are more money. I may order one and see how long it last. One note on my yellow pads. I had a BRAND NEW pad put it up against the bowl and "fling" there went the pad across the floor. Lets just says I really wanted to throw my drill against the wall last week! So I epoxied that one, now all of my pads in use are epoxied. They say to let the sandpaper do the cutting.......whatever.......if I let the paper do the cutting it will take a week to sand the bowl. You do need "some" pressure on the lower grits then back off more and more as soon as the tool marks are gone and all your then doing is trying to get the sanding marks out.

[Harry Robinette]

I bought some backer pads somewhere I think Cincinnati symposium a few years back that have holes in the middle,they look like donuts. I love these things they work really well and I believe they run a little cooler without the pressure in the middle.
That said I agree 100% with John K, light pressure, change paper often and slow down.

[Jim Burr]

To support the previous...let the sandpaper do it's job. A few things may help this along. An even, smooth grind on your tools. if you have a notch or groove...it will show on the wood. Slow movement and even finishing cuts eliminate ridges and lead to a better sanding experience...if there is one!

[Lloyd Butler]

One thing not to forget to help get rid from the potential for scratch marks is to try and finish off by power sanding with the disk running along the grain. You do not need to push hard, and I think you will have a little better success.

If you only sand cross grain currently, then give it a try.

I have had much better final results by doing the cross grain, then sand with the grain and than switch to the next grit. It can mean a lot of twisting and maybe awkward positions to stay with the grain, but give it a try.

Like the others point out, light pressure. You do not need to see the pad squeezed to 1/2 its thickness to think that it will work better. Have it compressed less than 1/4 its initial thickness and try that. Also, the drill can go top speed if you like, the lathe you want slow.

Lloyd

[Brian Kent]

As I do more, I think that I was not pushing too hard. I did however see that I was putting more pressure on the side.

[Kyle Iwamoto]

I have a mandrel/pad for the major grits I use. That way, the pad gets minimal change outs from grit to grit. That may also let the pad cool down. Easy to swap out the whole pad. I sharpie the grit on the pad so I know which is the next one.

I've melted backing pads velcro too. The bulk velcro from HD works as replacements.

[Brian Kent]

Great idea, Kyle.

[Scott Hackler]

Brian, I tend to sand with 1/2 of the pad as well and have torn up (or completely off) my share of the small yellow mandrels. I found that I pay a lot more attension to the amount of compression the soft yellow portion is getting while I am sanding and lighten up a bit. Think about the fact that the compressed portion isn't the part of the mandrel under stress... it's th eopposite side that is "stretching" and eventually tearing it.

I bought some of the white, short madrels from Vince while at SWAT but haven't had time to test them. I have super glued the yellow ones back together so many times, they dont squish much any more!

[Thom Sturgill]

To support the previous...let the sandpaper do it's job. A few things may help this along. An even, smooth grind on your tools. if you have a notch or groove...it will show on the wood. Slow movement and even finishing cuts eliminate ridges and lead to a better sanding experience...if there is one!

And that includes the flute of the tool. A ridge or groove in the grind of the flute translates to an uneven cutting edge and a potential ridge or groove in the surface of the cut.

[Phil Labowski]

Wow, so glad I read this! Now I know that I have to replace the velcro on my mandrel, get a couple interface pads and call Vince. I had the same problem as Jack Gaskin, brand new disc and mandrel (no interface pad though) and as soon as it touched the bowl...FWWEEEEEEEE off it went. I saw someone before mention using spray addhesive to help keep the discs on, just be sure to take it apart when done or you'll have a mess when you do try to remove it.

[Faust M. Ruggiero]

Brian,
In addition to all the above comments, it occurs to me that this thread ties into your thread about the dead drill. I've been using one of those red drills for three years and it shows no signs of wear. I suspect the pressure you are applying may be beating up the pads and the drill. It seems from your posts a lot of your work is sanded green. That takes more time since the sand paper is not as efficient when sanding green wood. Have you ever considered wet sanding with foam backed paper. The water makes the paper cut faster. Of course, this is hand held paper but with the water as a lubricant and accelerator the sanding goes fast. It's not a good way to "shape" your work but it works great to sand wet wood.
faust

[Prashun Patel]

One thing I haven't seen mentioned below is sanding with the lathe on. IMHO, it's frustrating to try to sand with the Neiko-style drills and a lathe that only spins down to 250rpm. 250 is just too fast. The sanding pad skips on the bowl - especially one that might have a modicum of warp from being turned green. This causes me to push harder, and it really torques the heck out of the mandrel. I sanded with the lathe spinning for a good long while, until I realized that it's quicker the other way. I was scared at first that I'd get undulations on the surface, but if you feather your sanding out properly, it doesn't happen. At the higher grits, the lathe on can be good to assist in burnishing, but to remove tool marks speed is not my friend.

One nice thing about sanding with the lathe off is that the heat generated is considerably less (less pressure required to engage the pad) which means less warp. On thinner bowls, most of my warping was previously caused during sanding.


I've had way better luck sanding with the piece mounted in the chuck, but with the lathe off and the indexing pin engaged. If you use a light touch - as is intended, switch paper when your gut says you probably should, and use many grits, you won't get any swirling. Your pads will last a long time this way.

Also, how firm is the pad on your mandrel? The firmer ones (with a radiused edge) are better for removing the tool marks at the initial grit stages than softer pads - even though the softer ones intuitively feel more appropriate for a curved surface.

Last, on the outside of your bowl, consider using your 5" ROS. It's way more efficient. There are several sites (I think even Vince's) that sell soft backing pads for a 5" ROS. This makes sanding the outside a breeze, and saves you having to get BARBARAic on your MANDRELs.

[Jack Gaskins]

I have found that I can start at 100 grit with lathe on at 250 (slowest mine goes) I use pressure and slow drill speed and side sweep movement of drill. I then stop the lathe and check for tool marks and tearout. If I have any I sand with lathe off just in those areas then after they are gone I turn the lathe back on to get an even scratch pattern again. I do this for the 100 and 120 grit after that Im good to go and just use light pressure starting at 150 on up with lathe on. One area I am having issue with is the very edge of the inside rim. Having problems leaving a crisp edge OR I end up leaving a few scratch patterns just at the very edge.

[Brian Kent]

When I sand avocado, I can keep the lathe on. But for most of the eucalyptus, the warping makes it really hard, so I do most of the sanding with the lathe off.