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Sanding Block Question

by gfadvm
posted 01-09-2013 12:57 AM


34 replies so far

View Grandpa's profile

Grandpa

3184 posts in 1364 days


#1 posted 01-09-2013 12:59 AM

I was taught to use a hard flat block on wood projects that have flat services. I have a couple of rubber pads but those are really made for sanding auto bodies so I keep them for that purpose.

View Handtooler's profile

Handtooler

1098 posts in 821 days


#2 posted 01-09-2013 01:18 AM

Thanks Grandpa for the advise on the rubber sanding pad block. I’ll quit trying to use mine which I originally acquired to work auto body many years ago.

-- Russell Pitner Hixson, TN 37343 bassboy40@msn.com

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Grandpa

3184 posts in 1364 days


#3 posted 01-09-2013 01:21 AM

I am not saying that is a bad thing to use the rubber pad but it does change to fit the contours you are sanding. Not like a rag but you know what I mean.

View John's profile

John

45 posts in 762 days


#4 posted 01-09-2013 01:50 AM

It depends on what you’re sanding. Ideally, the shape of the sanding pad matches the shape of your work. If you’re sanding a flat surface, a hard, flat sanding block is good. It also allows you to use it sort of like a block plane and make faceted edges vs. a softer block which will round off corners. A hard backing also allows you to put more pressure and really hog off material with a coarse grade of sandpaper.

I use firm rubber pads for a lot of tasks, and my shopmade wood blocks for others. I don’t bother with any backing on the wood blocks.

View RussellAP's profile

RussellAP

2959 posts in 975 days


#5 posted 01-09-2013 01:54 AM

If you think about it, any large surface you sand with a unpadded block will not conform completely to the surface being sanded. At least a couple layers of cardboard under the paper. You can get away with it on small pieces. I prefer ROS for large surfaces.

-- A positive attitude will take you much further than positive thinking ever will.

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TCCcabinetmaker

925 posts in 1044 days


#6 posted 01-09-2013 02:00 AM

I picked up a piece of granite once I was going to use for a sanding block once, but alas it dissappeared before I got it back home, it was in a trash bin too…

The key is you want your block to be harder than the wood you’re sanding so that it won’t wear, for profiles I typically use my hands, as I can make my hand conform to pretty much any profile so…

-- The mark of a good carpenter is not how few mistakes he makes, but rather how well he fixes them.

View Don W's profile

Don W

15240 posts in 1256 days


#7 posted 01-09-2013 02:01 AM

any i’ve made have been just wood (except these ) I didn’t put padding of any kind on them either, but I also haven’t really used them yet.

-- Master hand plane hoarder. - http://timetestedtools.com

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HillbillyShooter

4767 posts in 981 days


#8 posted 01-09-2013 02:05 AM

1/16” cork is what I use per Karson, http://lumberjocks.com/projects/15783 . By the way, this was my introduction to LJ.

-- John C. -- "Firearms are second only to the Constitution in importance; they are the peoples' liberty's teeth." George Washington

View vonhagen's profile

vonhagen

495 posts in 1054 days


#9 posted 01-09-2013 02:50 AM

before sandpaper the smoothing plane was used. i use 1 inch mdf or any scrap hardwood that is flat and contact cement the paper on, when the paper gets worn out i throw it away. when block sanding a flat surface you do not want any rubber or cork or anything soft as a backing. when contour sanding make a pattern block that fits your profile.

-- no matter what size job big or small do a job right or don't do it at all.

View gfadvm's profile

gfadvm

11239 posts in 1379 days


#10 posted 01-09-2013 03:09 AM

Thanks for all the replies. I had the feeling that my underlayment backing was causing my paper to snag and tear. I’ll try it without but I need to fill the hole in the center of the bottom or cover it with a thin strip of hardwood.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View jumbojack's profile

jumbojack

1199 posts in 1313 days


#11 posted 01-09-2013 03:14 AM

Since I make lot of boxes, I dont use a sanding block per-se. I glue a full sheet to a 15×20” piece of MDF and move the box across the full sheet. I have a full set 80, 100, 150, 180 and 220. It really helps to keep the flat parts flat.

-- Made in America, with American made tools....Shopsmith

View Clint Searl's profile

Clint Searl

1474 posts in 1050 days


#12 posted 01-09-2013 03:15 AM

I have two sanding blocks that are dimensioned such that I can hand hold a quarter sheet of paper. I faced one with truck inner tube and the other with 1/8” sheet cork.

-- Clint Searl....Ya can no more do what ya don't know how than ya can git back from where ya ain't been

View grizzman's profile

grizzman

7099 posts in 1992 days


#13 posted 01-09-2013 03:21 AM

i like the sheet cork also andy, but to each his own, i like a little bit of cushion that the cork gives…

-- GRIZZMAN ...[''''']

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bluekingfisher

1058 posts in 1669 days


#14 posted 01-09-2013 09:01 AM

I would tend to use just the bare block Andy. Of course it could depend on what you are sanding I would have thought. Straight and flat, bare block, any coutours then some form of “padding” may be more appropriate.

Too much of a cushion may not sand the area flat and simply follow the contours of the piece, much like a smoother plane on a long wavy board.

-- No one plans to fail, they just, just fail to plan

View gfadvm's profile

gfadvm

11239 posts in 1379 days


#15 posted 01-09-2013 04:44 PM

I’m gonna try the plain wood backing and report back to y’all.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View Clint Searl's profile

Clint Searl

1474 posts in 1050 days


#16 posted 01-09-2013 05:42 PM

It’s a specious argument that Too much of a cushion may not sand the area flat and simply follow the contours of the piece, much like a smoother plane on a long wavy board.

If the surface ain’t already flat, rubbing with 100 or 180 sandpaper won’t get it flat. Plus without a bit of cushion, the paper will tend to load and glaze, especially around the edges, leading to premature failure.

-- Clint Searl....Ya can no more do what ya don't know how than ya can git back from where ya ain't been

View John's profile

John

45 posts in 762 days


#17 posted 01-09-2013 06:48 PM

Hmmm… Clint and Russel raise a good point. Unless your work surface and your hard sanding block are both exactly the same shape, then you’re only sanding with the spots that actually make contact. I guess it depends on the goal. If you’re shaping the surface, you want a more rigid pad that’s the shape you want – flat, wrapped around a dowel, glued to a curved block, whatever. And it seems like it would really pay to take the time to get the shape right, eg. flattening a wood block like a handplane sole.

If you’re smoothing a surface for finish prep, then a softer backing will use more of the abrasive surface and allow the sandpaper to conform to whatever shape the surface is, thus sanding the entire surface. With a hard block, any low spots in an almost flat surface won’t get sanded.

View nwbusa's profile

nwbusa

1017 posts in 975 days


#18 posted 01-09-2013 07:03 PM

I keep a few of these loaded up with various grits. Best sanding blocks I ever used.

-- John, BC, Canada

View frosty50's profile

frosty50

27 posts in 1036 days


#19 posted 01-09-2013 07:05 PM

I made up several as Christmas gifts for friends this past year and have several in my shop of various sizes and shapes. For a padding I bought the non-slip drawer liner material from a big box store. I attached it using 3M 77 spray adhesive. The padding can be replaced when worn out by peeling and scraping it off. The padding allows a little forgiveness when sanding and I think the paper last longer and does not tear as easy. I made up 1/2 and 1/4 sheet ones, and have a couple of speciality ones (round and cove types). I use to use ones without the padding and would tear the sanding paper. Most of the people I gave them too really like the padding, have had several compliments about them.

-- frosty

View dhazelton's profile

dhazelton

1217 posts in 986 days


#20 posted 01-09-2013 08:36 PM

A friend of mine makes blocks that hold a sanding belt. Don’t know the exact size belt off hand, maybe 4 inches wide by 24 as the blocks are over a foot long (made from MDF). They are best at edge sanding rough cut wood or when trying to back plane a cabinet frame during installation.

View pintodeluxe's profile

pintodeluxe

3446 posts in 1502 days


#21 posted 01-09-2013 09:11 PM

I use small sanding blocks with self adhesive sandpaper on two adjacent sides. I use it like a shoulder plane to fit tenons. I also use it to ease sharp edges and corners.

As far as tabletops and flat panels, I just use my 5” ROS and work through the grits. I find it leaves a nicer, more uniform finish than a sanding block can.

Good luck

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View bondogaposis's profile

bondogaposis

2599 posts in 1040 days


#22 posted 01-09-2013 09:17 PM

I use both. If I want to maintain a flat surface I use a straight wood block but for contours and round overs I like to put a piece of 6mm craft foam between the block and sandpaper. Another super sanding block material is cork. It has just enough “give” and really helps the paper to cut.

-- Bondo Gaposis

View jap's profile

jap

1232 posts in 743 days


#23 posted 01-09-2013 09:34 PM

i use any block of wood from the scrap bin, but for sanding between coat of varnish i sometime will put a piece of padding between the block and paper.

-- Joel

View Handtooler's profile

Handtooler

1098 posts in 821 days


#24 posted 01-09-2013 11:45 PM

Klingspore even sells and recommends 1/2’ and 1” H&L pads for ROS’s (5” 8 Hole and maybe some other designs) to be used on contour projects. Anyone of you LJ’s ever equipped your sanders w/ such?

-- Russell Pitner Hixson, TN 37343 bassboy40@msn.com

View gfadvm's profile

gfadvm

11239 posts in 1379 days


#25 posted 01-10-2013 01:31 AM

Wow! Lots of opinions. To clarify: all the surfaces I’m concerned with should be flat (planed and drum sanded to 120 grit). Interesting that several of you suggest padding to prevent tearing the sandpaper. I’ve never tried unpadded blocks so looks like I’m gonna have to try them and decide which works best for me. Thanks for all the interest and comments.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View Grandpa's profile

Grandpa

3184 posts in 1364 days


#26 posted 01-10-2013 03:15 AM

If you have a high place like putty to sand or if you are sanding a wood with wide grain and hard/soft grain (like yellow pine) Then a flat block will work better that a soft block. When you said a padded base my mind instantly went to some thing like a sponge. Look at the sanders available to buy. Both power and hand. They have a thin layer of rubber or something like that on them. They will make contours if you aren’t careful though. I like my felt based sander. It is softer than oak and yet a mild pad.

View vonhagen's profile

vonhagen

495 posts in 1054 days


#27 posted 01-10-2013 05:31 AM

the whole idea behind block sanding is to do final sanding on a surface that has already been shaped or flattened. a padded baking will roll edges because as you go over the edge the pressure is released and the pad will naturally want to go over the edge and break it and cause burn thru on veneers. on solid wood a padded block will ruin a machined flat surface. on inside and outside radius work, cima, circa, a block can be made by tracing the profile onto a block, rough cutting on the band or scroll saw then reversing the sandpaper on your profile and sanding your block to that profile then applying the paper to the block with contact cement and when its time to change paper lacquer thiner will take off the paper there is elastic sandpaper for contour sanding raised panels and other profiles on an aluminum head is used on a slow speed shaper type machine used in door manufacturing and again no padding is used. then we have the widebelt sander with multiple heads. the first head flattens with a course grit the following heads can do several different things and this is where the padded flexible platen is used because plywood panels are not flat and the panel thickness varies more than the thickness of the veneer so the platen has fingers controlled by air and electronics and follow these hills and valleys in the panel without burning thru the problem is the outside edges can get rolled and burn thru but with proper adj. of air pressure and timer settings you can get excellent results.

-- no matter what size job big or small do a job right or don't do it at all.

View dbray45's profile

dbray45

2536 posts in 1466 days


#28 posted 01-10-2013 06:15 PM

I rarely use sandpaper but I do use a sanding block. Let me explain—

I bought some 1/4” cork from Walmart and glued it to a piece of 2×4, about 3” long – easy to handle – a sanding box. I put an old rag that has no dye in it and wrap it so the cork bottom is covered tight.

After my surface has two thin coats of finish, I pour some mineral spirits on the surface, sprinkle a fair amount of pumice on the mineral spirits and use the block gently to polish in a figure 8 pattern across the whole surface. I clean it off, add more finish, dry, and do this again with finer grit pumice. After the fourth or fifth time, I finish using rottenstone, spirits, and a cloth – no block.

The idea is to get a flat mirror finish – its a little bit of work but the results can be really nice.

-- David in Damascus, MD

View gfadvm's profile

gfadvm

11239 posts in 1379 days


#29 posted 01-11-2013 01:25 AM

Thanks Blaine- Was wondering if you had dropped off the face of the earth! No padding on blocks when sanding finishes either????

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View vonhagen's profile

vonhagen

495 posts in 1054 days


#30 posted 01-11-2013 09:52 AM

im still here andy lol, wet sanding with fine paper with a dynabrade on full fill just enough to get the nubs out or by hand wet sanding contours. final buff with micro finishing compound wet. elk skin and tin oxide mixed with water and hand rubbed wow!

-- no matter what size job big or small do a job right or don't do it at all.

View Tim Dahn's profile

Tim Dahn

1473 posts in 2254 days


#31 posted 01-11-2013 11:00 AM

I have been using foam sanding blocks for a few years now, here is the review I did a while back;
Hand sanding
They work great and the result is perfectly flat blemish free surface. The ones from northern tools (cheaper version) have held up as well as the Bush version. I have not experienced the edges rolling over as vonhagen describes but there is a harder layer on the bottom where the psa sandpaper adheres to.

-- Good judgement comes from experience and experience comes from poor judgement.

View vipond33's profile

vipond33

1405 posts in 1187 days


#32 posted 01-11-2013 12:02 PM

I use sanding blocks of all types at work and they all have their strong points and limitations.
Pure hard blocks Titebond glued to (checked for dead flat) MDF are perfect for cross grain leveling and careful joint preparation (or correction). Also great for accurately grinding down projections (dowels, tenons, lapped edging). I use “C” weight paper. The downside is that they wear quickly, develop corns or glaze parts of your surface. Un-excelled though for careful corner easing and accurate edge rounding.
Padded blocks include 1/8” or 1/4” cork and also hard leather. These keep surfaces essentially true while reaching down to sand all areas and have the advantage of allowing the paper to bite as it flexes under load. You are minutely rolling the microscopic particles to engage more than one cutting edge. This also clears the paper of swarf much easier giving longer life and less churning of the dust. Knock them out frequently. I have dozens of different shapes and sizes of these using PSA paper. Easy on, easy off.
My daily heavy use block though (for regular paper) is a 3×5 chunk of 1” stiff blue insulation board. Soft in the hand, light to use and drop it a hundred times with no damage. I true it up periodically on the belt sander and throw it out when too thin. This material is easily reversed formed for custom curves. Did I mention fast and cheap?
My most common mistake using any softer block (and I never seem to learn) is forgetting to turn up the leading edge slightly so as to not dig in and catch under angled grain. Plenty of fresh sanding after the repair!
gene

-- gene@toronto.ontario.canada : dovetail free since '53, critiques always welcome.

View vonhagen's profile

vonhagen

495 posts in 1054 days


#33 posted 01-11-2013 06:00 PM

use sharpening your chisels as a reference. your stones must be flat, you start by flattening the back of the chisel with coarse to very fine and then do the bevel. what creates the final burr and what would happen if you used a padded abrasive? i know there are a few of you out there that use a belt sander to sharpen your chisels, shame on you. now sharpen your chisels using a flat block of hard maple with wet or dry sand paper and tell me the results. now apply this process to block sanding wood and what happens?

-- no matter what size job big or small do a job right or don't do it at all.

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gfadvm

11239 posts in 1379 days


#34 posted 01-12-2013 01:37 AM

Gene and Blaine- I much appreciate the input!

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

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