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End grain sanding help, please!

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Forum topic by Debbaann posted 05-08-2018 04:36 PM 2782 views 1 time favorited 10 replies Add to Favorites Watch
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Debbaann

2 posts in 413 days


05-08-2018 04:36 PM

Topic tags/keywords: end grain sanding burnish question sander

Neophyte here, so apologies in adavance for what may be just another dumb question to the masters…I’m working on an end grain CB-(maple, purpleheart, canary, wenge, etc). Started w 80 grit on the belt sander and got it fairly smooth, but now I can’t get ANYTHING off of it with 80 or 120 using the belt sander or ROS. There’s a shine on it but it’s definitely not done-still needs some flattening and scratches/blemishes are visible…when I spray a bit of water on it, it still feels very rough. After sanding for a couple of hours yesterday, I thought it (or I) might just need to cool off for awhile, but today it’s more of the same…not even the slightest bit of dust is raised with medium pressure. Did I kill it with heat from the belt sander? I’ve read some other posts about burnishing… it’s like it’s somehow SEALED. I know end grain takes a lot of time and patience, but this doesn’t seem right to me. Is there any way to recover from this without bearing down so hard I cause more damage?


10 replies so far

View BorkWood's profile

BorkWood

14 posts in 446 days


#1 posted 05-08-2018 05:11 PM

Did you try sanding it some while wet? Sounds like you may need to take a layer off with a drum sander or router flattening sled.

-- Matt, Woodworker based in NC, https://www.BorkWoodBlog.com

View EarlS's profile

EarlS

2799 posts in 2742 days


#2 posted 05-08-2018 05:24 PM

Put a new belt on your sander. The grit on the belt is probably worn down and loaded full of fine sawdust and resin from the wood. So you are likely getting burnishing as you mention. There are belt cleaners that look like giant erasers that will clear out most of the build up on the sand paper.

I’d also suggest that you might be ready to move to a finer grit. If you are sanding for hours something is definitely wrong. Spraying water on wood that has been sanded will bring up the grain unless it has been sanded with really fine grit and even then there is some raising that occurs. Hopefully, this helps.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

View TechTeacher04's profile

TechTeacher04

411 posts in 1925 days


#3 posted 05-08-2018 06:42 PM

I agree check your sandpaper. If you have a low angle jack plane you could also use that to help flatten the board. Based on the woods you used I do not think you have loaded up the paper with pitch.

How long did you let the board dry before sanding? If you had any residual wet glue you could have glazed your sandpaper with glue.

View John Smith's profile

John Smith

1834 posts in 556 days


#4 posted 05-08-2018 09:10 PM

can you post some photos of your project and issues ?

-- Failure is proof that you at least tried ~ now, go do it again, and again, until you get it right --

View nutmegger13's profile

nutmegger13

19 posts in 658 days


#5 posted 05-08-2018 10:58 PM

I use a cabinet scraper with pretty good results instead of a very coarse sandpaper. Then move to 100 or 120

-- nutmegger13, Connecticut

View Debbaann's profile

Debbaann

2 posts in 413 days


#6 posted 05-09-2018 12:23 AM

Dried the board 24 hours before sanding, and I’m good about trading out the sandpaper-actually I’m probably guilty of tossing it too soon (15-20 min w 80 grit on the belt sander)-husband is always telling me “that’s perfectly good!”...which goes to an argument about how we’re not in a damn depression-but that’s a different post. I did try wetting it-I half wondered if that had done something. Started at 80 grit and moved to 120. The belt sander does get very hot very fast with very little pressure. Photo shows the shine on it-not sure if the scratches are as clear.

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John Smith

1834 posts in 556 days


#7 posted 05-09-2018 01:09 AM

that is going to be a good looking board when it is all said and done.

.

-- Failure is proof that you at least tried ~ now, go do it again, and again, until you get it right --

View LesB's profile

LesB

2093 posts in 3837 days


#8 posted 05-09-2018 03:57 PM

You are sanding some very hard wood so fresh sharp aluminum oxide sand paper is a must. As the wood gets smoother it is harder for the sand paper to dig in and cut the hard end grain so be patient. Belt sanding this type of surface usually works better when the sander is applied on the bias or angled to the direction of the wood pieces. To remove scratches I usually use an orbital sander starting with 100 grit and then 150. If I’m looking for a very smooth finish I will go to 180 grit. Because the grain in your wood pieces seems to be in random directions a straight line belt sander will not do well at removing all the scratched across the grain and those pieces will continue to show some scratching. The orbital should take care of that.

-- Les B, Oregon

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BoardsByBullard

22 posts in 722 days


#9 posted 05-09-2018 10:33 PM

End grain is HARD on sandpaper, I can’t stress enough that the quality of your sandpaper and setup is the key to your success. I was heavily (hah, or so I thought) invested in the bulk packs of Diablo Sandpaper (~$.40/sheet) from Home Depot and constantly frustrated with the life of the paper. I also learned that if you don’t have your sander hooked up to some sort of vacuum you will burn through sand paper significantly faster regardless. You can get away with having a bag attached for a quick touch up on a flat panel glue up but end grain will eat paper very quickly without a vacuum, especially for a belt sander. If you don’t frequently dress your belt (clean it with a gum rubber stick) and have a vacuum going you will quickly turn your belt sander into a belt burnisher, literally polishing the end grain like you have done. I’m certain that if you just get a new belt you should be able to break through.

I make a lot of end grain boards in my shop (funds the shop itself) and while I now have a drum sander for flattening and smoothing my boards I started out with a hand plane and 5” Rigid random orbit sander I still remember when I upgraded to a belt sander for initial flattening. The belt sander was my first aha moment for the importance of sand paper quality, a cleaning stick and a vacuum… I needed to pick up belts and happened to be closer to a hardware store that stocked Norton Belts so that’s what I purchased. I’m still on my original cleaning stick (now used for the drum sander) about almost a year later and still have all of the belts I purchased initially.

A few tips, (looks like you are already past this point but…)

  • Avoid the super low grits, I’d much rather spend an extra 20 minutes flattening with a 100 grit belt than spending an hour trying to get 36-60 grit scratches out of end grain
  • Clean your belt often
  • Flip the board often so you don’t overheat it and cause it to warp (this quickly leads to compounding errors, you warp it, sand it flat, it unwarps as it cools and is more warped because the areas you sanded flat are now thinner etc…)
  • With a belt sander don’t try to bother trying to get it perfectly square (eg parallel faces) close is close enough lest you end up shaving off an inch of thickness… Flat is the goal ;)
  • Sand to a much higher grit with the belt before falling back to the Random Orbit Sander to clean up the lines. (I sand to 150 with the drum sander, 220 with a belt sander)
  • When you come back to clean up the lines with a ROS start at a lower grit like 100 and then work your way up to your finishing grit my workflow is 100g (rotary mode to obscure deep scratches) > 100g (Random Orbit Mode to hide the rotary swirls) > 120g > 150g > 220g and finally polish with 320g because it makes me feel ok charging a small fortune for these things)
  • If you can swing it a 6” ROS will make your life WAY easier as you significantly more surface area (113”sq vs 78.5”sq) , especially if it has a rotary sanding mode like a Rotex or Bosch 1250DEVS. A sander with build in vibration dampening will save your wrists…

If it matters at all my full workflow:

  • Cut and glue, flatten, clamp for 4-5 hours, scrape glue with a chisel, dry for at least 12, usually 18 hours – repeat as the pattern calls for it
  • Initial flattening on the Drum Sander (Supermax 19-38) with 80g paper. I make most of my boards in pairs so I send A through, B through, flip A and feed through, flip B and feed through, repeating until both boards are flat (obviously if one is flat before the other take it out of the rotation). I do this to keep the boards from overheating… Once flat I work from 100g > 120g > 150g making sure to finish with very light passes to minimize tracks (which are unavoidable with belt/drum sanders)
  • Trim edges on the table saw (I have all but given up on trying to make a board square to its pattern because I have learned that a customer would generally rather have a larger cutting board than a perfectly aligned board), Using my crosscut sled I trim one edge so I get a 100% pass by the blade, using it as a reference face for cutting all the other edges. The only time I trim again is due to an edge glue up flaw, eg visible crack which will need to be cut out.
Finishing:
  • Bosch 1250Devs Sander in Rotary Mode – 100 Grit focusing on any sanding tracks
  • Bosch 1250Devs Sander in Random Orbit Mode – 100 sanding overall board+
  • Bosch ROS60vc – 120g > 150g (don’t forget the edges!)
  • Route Edges (1/4 or 1/8” round over)
  • Bosch ROS60vc – 220g
  • Bosch ROS20vc – 320g Polish

Dump the board in a vat of Mineral Oil for 20 minutes (protip USP food grade mineral oil at walgreens is $5.99/16oz you can get it on amazon for $21/Gallon) let it sit out in the air for a day or so, finish with beeswax/mineral oil and get it ready for sale…

As far as sandpaper goes I went all in on 5” Norton MultiAir discs (80g-220g ~$.80/disc/50-pack) for my 5” sanders and since switching to 6” sanders (literally 2 weeks ago) I am trying Mirka Abranet discs (100g-220g ~$.90/disc/50-pack) which are holding up very well. I can usually get at least a single cutting board out of a 5” disk (pretty much regardless of grit) and I get at least 2 boards with per disc with my 6” sanders. Please note that as stated above I run my boards through the drum sander up to 150g then back down to 100g to get the streaks out finally working back up to 220g.

I finished these two boards with 4 sheets of sandpaper last night…

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OnhillWW

184 posts in 1626 days


#10 posted 05-09-2018 11:18 PM

Beautiful boards. Very well done and comprehensive write-up,

-- Cheap is expensive! - my Dad

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