Flattening an End Grain Cutting Board – Patternmaker Method

[Randy Benway]

When I started my wood patternmaking apprenticeship at Caterpillar in the Spring of ’81, it was Wacko World at first. I had completed an apprenticeship in my dad’s mill/cabinet shop in the 70’s (just before the economy tanked) so was very familiar with many of the wood machines and processes. Some were foreign though. The big disc sanders were completely new to me and I soon learned they were the work horses of the pattern shop.

Cat’s pattern shop had 50 journeymen; I was one of 3 apprentices. Some journeymen had served their apprenticeships right there at Cat. Others came from around the globe and all aspects of industry. The shop was air conditioned, well lit, and quiet. Four banks of duplicate machinery was laid out evenly so you never had to go far to find an open machine. The lumber rack area was in one corner of the shop; it was ~100ft long and 2 stories high loaded with 8/4 mahogany, Perfect Plank pine, and plywood up to 2” thick. That area also housed the “rough” processing machines: 24” jointer, 36” planer, 16” ripsaw (all Oliver), and a 18” RAS.

Each steel bench had a 8’ maple top, an Emmert vise, a back frame to affix drawings, and a 3’X4’ granite surface plate to the side. On day one, I was assigned a bench and given a drawing to make. It was a simple core box. Thankfully, all the journeymen around me were friendly and most helpful. After some discussion about what a core box is (ha) and a possible build approach, I went off to prepare the wood. I came back from the lumber area with some mahogany boards face jointed and planed thinking I was ready for the next step… wrong!

Journeyman- “It’s not flat enough.” Me- “But I face jointed it.” Him- “Jointers don’t get things flat enough.” Day 1, lesson 1: flat to a cabinet maker is NOT the same as flat to a wood patternmaker! How do you flatten?... “On the disc sander.” Wacko World! Each machinery bank at Cat had a large disc sander. Three banks had a 30” Master; one bank had an Oliver 34” double disc. These things were 2000 lb behemoths! They ran all day and were dead quiet.

My dad’s shop had a 6X48 Delta combo sander with a 12” disc on the side. The abrasive flew off the disc years back and he never replaced it. The stationary belt was the only thing I had ever run. Who cares right? A belt can do anything a disc can but without the “swirls” I thought. Also running through my head was the lesson from my dad that “sanders don’t sand flat.. they always round over.” Now, this patternmaker is telling me to go flatten on a sander??? Wacko World. I didn’t believe him so I nicely challenged his premise. He smiled. He had me face joint a 4’ plank; he faced the other side on the sander. Testing flatness is done by “hinging” the stock on a surface plate. Yeah, I lost.

You quickly learn that disc sanders CAN sand flat… and straighten stock too! Just like learning to run a jointer or a belt sander… you need to learn the necessary stroke. Starting the “cut” on the downhill side of disc, you smoothly move the stock across the disc to the uphill side and back. Minimal force is required. Contact is maintained across the disc. You’d think the uphill side would lift and throw the stock…. It actually wants to “turn” with the disc but won’t if you apply a light downward force keeping it to the table. The stroke can be practiced moving the stock across the disc with the machine off. A disc should be setup to “cut”: large machines get 40 grit, medium 15”-24” get 50 grit, and 12” discs perform well with 60 grit. Change the abrasive when it wants to burn end grain. This skill was pounded into the young patternmakers. Now I’m old and retired and still do it often.

I’m writing this because it seems this skill has been lost (like many patternmaking techniques). A friend recently retired and started woodworking as a hobby. He made his first end grain cutting board this year and struggled getting it flat. He said he spent hours working away on the random orbit. He reads a lot and watches woodworking videos (which I don’t) and mentioned some WW’s run their end grain boards through the planer (wow)… some use drum sanders… and some build router sleds. All possible solutions but he has a 12” disc… so I mentioned that he should learn to flatten on that. He practiced the stroke; now he’s a pro!

I recently made a cutting board for the Fall raffle at church and made a video to share how I flatten using this process.


https://www.youtube.com/shorts/YehlcEdHj-8

For years I used a 12” Delta disc. The cutting boards were always taller than the disc! No biggy. Using the same stroke, I just make 2-3 passes along one edge turning the board 90 deg (to the next edge) to make additional passes, keeping the cut uniform. This video shows flattening strokes along each edge to complete “once around” the board (50 sec) on a State D16 sander. Most end grain boards are cleaned up and flat in 3 trips around the board…. about 2-3 minutes. Ready for final sanding!

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[Andrew Hughes]

I have not see that way before very interesting. I’ve thought about getting a disk sander but they seem to be made from gold. The ones I like the best are too expensive.
I also like your woodworking back ground report. I wish you were my neighbor. The neighborhood I live in people are surprised when I mention wood actually comes in more then one color.
Good Luck

[Maurice Mcmurry]

My eyes glaze over on some long posts... I enjoyed every word of this one!

[Philip Glover]

Randy,

Wow!
Thanks for posting this.
I am going to try this first thing tomorrow.

Regards,
PCG

[Cameron Wood]

Great info!

Got more?

[Mel Fulks]

I worked in pattern shop for a couple of years. Owner was older so I guess he’s gone now. German , real picky. I don’t see the big
spinning wheel sander better than a jointer, it just does a different job. Guy was always decreeing a different draft angle for every pattern
part . 5 degrees here , 2 there…

[Richard Coers]

I was a modelmaker at Cat. Stated in Bldg F in the Tech Center, moved to AC in Mossville when they outfitted us with a whole new Industrial Design dept. Retired in 2014.

[John K Jordan]

Randy, thanks for this. I often use my 12” disk sander to flatten things but had never imagined using it for something larger.

[Steve Demuth]

Journeyman- “It’s not flat enough.” Me- “But I face jointed it.” Him- “Jointers don’t get things flat enough.” ... I didn’t believe him so I nicely challenged his premise. He smiled. He had me face joint a 4’ plank; he faced the other side on the sander. Testing flatness is done by “hinging” the stock on a surface plate. Yeah, I lost.

And these were patterns for casting metal parts? Like a core box that is going to have a combined shrinkage and machining allowance of 1/8" or more? I can appreciate the craftsmanship involved, but does it really matter?

[Randy Benway]

Thanks for the kind words everybody! Sorry this post went so long but I felt it needed some background... before patternmaking, I would have howled at somebody telling me to flatten on a disc sander!
More details:
- Note on the video that I had to raise the dust shield on my State to access the full disk. This makes the machine much dirtier. When raised, my machine throws dust to the right. I usually stand a 8' length of plywood for it to fling against. Cleanup is easy then. Commercial shops usually REALLY pore the dust collection to the lower AND upper sections/shroud of a disc to keep them clean.
- Once the board is flat, I lower the dust shield and apply the usual stroke around the edges to clean them up and straighten:


https://www.youtube.com/shorts/4mdIjqCFc0o

- I mentioned "hinging" to check flatness. It was a lesson on day 1. Some of the journeymen at Cat called it "waggling". Check out machinist extraordinaire Keith Rucker illustrate "hinging" @ 11:35 min

https://www.youtube.com/watch?v=amj4FGqCfQY&t=757s

This is an important concept. Hinging was done right at the sander table so you could monitor progress and make adjustments on the next stroke. The sander table has to be flat too though!
- Another early lesson was that patternmakers use knife or scratch lines to mark the work... never pencil lines. This is done for accuracy when at the disc or spindle sander. You would see just 1/2 of the knife line just "drop away" when met. I'm not sure my old eyes can do that anymore!
- Cat had an Oliver #12 patternmaker's jointer. It got new knives every other Monday morning. 8/4 Mahogany always had that characteristic "crack" when you used it. A patternmakers jointer has the feature of allowing the infeed table to twist.. producing draft tapers. Guess what??? It was never used. Draft angles were almost always made on the big disc or spindle sanders. They were more accurate.
- Yes, grey iron shrinks at 1% (or 1/8"/ft). Getting and keeping things flat wasn't just about accuracy (although that is important). It was also about building a stable pattern that maintains it's accuracy. In my second year I was put on a team to build first patterns for the then new 3600 V12 variant engine block. The main pattern was so big you could walk on it! Multiple patternmakers worked on multiple tooling components at once. I was given a fairly large core box to make. Accuracy was very apparent when the foundry drew the molds and started setting cores. The cores had to maintain proper metal wall across multiple components. The pour went great and made a good casting on the first try. It took 5 days to solidify! In the layout room, ALL DIMENSIONS WERE IN SPEC. Great memories!

[Edward Weber]

One point to make is that while your method does flatten one side, it does not keep uniform thickness in the piece the way a planer and/or drum sander does. Care should be taken to avoid making a lop sided piece.

[Philip Glover]

I tried this today on my 20" sander and it works well. The dust, however, was all over the place!
Now I understand why some of the 36" sanders I have seen have the dust shields that they do.
I do not see a way to maintain uniform thickness the way a planer does. If there is a way, other than hand planing, I would be very interested.

Regards,
PCG

[Randy Benway]

One point to make is that while your method does flatten one side, it does not keep uniform thickness in the piece the way a planer and/or drum sander does. Care should be taken to avoid making a lop sided piece.
Yes, that is called "mastering a machine". It used to be done by following a journeyman's guidance, making mistakes, and learning to overcome them. That's another process that seems to be lost. It took me 2 years to learn to run a belt sander. At first it was EASY to make lop sided pieces... then I got better. Know that the disc is way easier to learn. The journeymen used to say "use your pattern makers touch kid." It can be dirty though! I close all the other blast gates to give "full chooch" to the sander. I also keep the table raised so more of the lower DC air will flow from the upper shroud. Surprised at the comment of maintaining parallelism though... each pass around the board is only taking .003-.005"... it would take hours (and on purpose) to cut an end grain maple board "lop sided".

In the pattern shop after the work was flattened on a disc, an overarm router was used to control thickness. End grain pieces could be done too with special sanding heads (shop made). These things are formidable... some would say terrifying and way beyond the scope of this thread.

Funny you mention drum sanders. The first end grain boards I made (about 8 years ago), my wife wanted 3 made (for gifts). Everything went well until I took them to a local shop for them to run through their wide belt sander for clean up. I wasn't allowed back there to watch but the bright white maple I had chosen so carefully came back dark and glazed. I was so upset. That's when I decided "never again"... I can do this better in my shop with processes I can control.

The lesson learned: end grain maple is tricky. Use sharp abrasives. Keep the heat down. Don't skip any grits. Different strokes... this may not be for you! Good luck!

[Michael Justice]

Thanks, Randy, for a trip down memory lane. My dad was a patternmaker - after the factory closed he started a small pattern shop in our basement. Watching him work left me with a love of woodworking and cherished memories. My shop has his Emmert vise, assorted Buck Brothers chisels and some shrink rules, but unfortunately only a fraction of his skills.

[Warren Lake]

Thanks for that info. I always appreciated the stories from the old guys. Both them and their stories helped me over the years many times. They had simple ways to get good results. It was also clear we had teachers who didnt have as much to offer compared to others because of where apprenticeships were done and then the next 40 years of what shops they worked in. When you charter two boats to go to Burma to buy teak for one job you are running at a pretty big level and have to know your stuff, it becomes a legal responsibility as well.

That takes good skill what you have done there. I dont understand what you are starting with as it looks like its perfectly glued up already other than a number of stains that appear from some glue. Im sure other cutting board guys are starting with nothing that true.

If i was only allowed one sander it would be a stroke sander, second addition would be an edge sander, last a wide belt, im sure i could find uses for a disc as well. Ive watched some Wadkins sell at auctions but I usually pay less for cars.

[Rob Luter]

Brings back memories. Right out of college I designed tooling for open top vinyl molding. The aluminum molds had to account for vinyl shrink and draft angle, and the fact that the aluminum would expand when it got hot and the vinyl plastisol was poured in. My mold drawings went to a pattern shop, who also had to account for aluminum shrink and draft angle. They were a great bunch to work with. Bill Wendel was the second generation owner of the business (Wendel Pattern). He was a great guy (RIP). The shop was full of vintage equipment that had been powered by belts from a ceiling mounted Jack shaft when his Dad started the business. They were electrified in the 1960s.

They had a lumber room that was to die for. A rail car size room full of 8/4 clear Honduran Mahogany. They were right around the corner from Gibson Guitar in Kalamazoo and Bill bragged that they had better quality wood. What I would give for a few of those boards now.

[Randy Benway]

That takes good skill what you have done there. I dont understand what you are starting with as it looks like its perfectly glued up already other than a number of stains that appear from some glue. Im sure other cutting board guys are starting with nothing that true.

If i was only allowed one sander it would be a stroke sander, second addition would be an edge sander, last a wide belt, im sure i could find uses for a disc as well. Ive watched some Wadkins sell at auctions but I usually pay less for cars.
Hi Warren,
After making a few boards with an odd mis-alignment here and there, I prepped a few cover cauls lined with packing tape. Now they come out of the clamps pretty decent. A "bumpy" board is straightened up pretty quick on the disc though... a disc takes the tops off in no time. More trips around the board on the divot side!

Your sander list is exactly what my dad would have listed! He'd throw a portable belt sander in there too. YOUR list requires skill as well. Stroke sanders don't just run themselves.... takes a while to master!

Cat began closing the Mapleton pattern shop in the mid 80's... being a lowly apprentice, I got let go first. I quickly found work in a pattern job shop specializing in aviation work. F14, F18, etc patterns were commonplace. That shop had a 36" Wadkin double disc; wonderful machine (way better than the Oliver double... equal to the Master). Each bench had it's own State D16... I've been searching for one ever since! Found one 3 years ago ($600). Now I'm soooo spoiled!

[Warren Lake]

Id get along with your father. My first stroke sander was the Rockwell 3 x 21 belt sander. I bought it used in 81. It got used really hard over the years. Its proof that US made some really great quality tools. It still gets used for certain stuff. Take the tool to the work stuff.

I built the first stroke sander. Second got a Progress then progressed to an Italian machine. Yeah you need some feel on a stroke but they can do so much. I don't use the traveling arm. Different hand pads different hardness's made to suit.

[Dan Friedrichs]

Great stories and fantastic video. Thank you, Randy!

I'm struggling to understand, though.

I always thought of a disc sander as kind of a weird tool, since the center is moving slowly and the edges moving very fast (linearly) - so if you held a board up to it with constant pressure, you'd sand it into a wedge. Obviously you aren't doing that in the video because you're moving the board back-and-forth along the disc, but it just seems like an inferior tool design compared to, say, a widebelt or drum sander where the cutting speed is uniform across the abrasive?

As far as a tool for flattening, why would it give a flatter surface than a jointer? It seems like the ability to get a board flat is from your identification of high spots and finesse in hitting them with the disc. Wouldn't a handheld belt sander give the same result?

To be clear, I'm not challenging what you're saying - those results speak for themselves! I've just never used such a sander and would like to learn.

[Maurice Mcmurry]

Getting things truly flat with a hand held belt sander has been a very big challenge for me. In fact I have chalked it up as being close to impossible.

[Randy Benway]

Great stories and fantastic video. Thank you, Randy!

I'm struggling to understand, though.

I always thought of a disc sander as kind of a weird tool, since the center is moving slowly and the edges moving very fast (linearly) - so if you held a board up to it with constant pressure, you'd sand it into a wedge. Obviously you aren't doing that in the video because you're moving the board back-and-forth along the disc, but it just seems like an inferior tool design compared to, say, a widebelt or drum sander where the cutting speed is uniform across the abrasive?

As far as a tool for flattening, why would it give a flatter surface than a jointer? It seems like the ability to get a board flat is from your identification of high spots and finesse in hitting them with the disc. Wouldn't a handheld belt sander give the same result?

To be clear, I'm not challenging what you're saying - those results speak for themselves! I've just never used such a sander and would like to learn.
Hi Dan,
Well stated! I felt the same way walking into the pattern shop. "This is so weird! Sanders don't flatten... and disc's leave swirls!"

It works because you NEVER leave the workpiece static... it should always be moving and maintaining light contact across the disc. Good disc sanders are pricy too because you're essentially buying a precisely ground spinning plate (with minimal runout) mounted to a "surface plate" table using very accurate ways. It takes some practice to master the stroke though. Remember, there is flat... and then there is flat. Most woodworkers don't need to be that accurate. Drum and wide belts are made to produce good finishes with minimal operator skill. They do that well. They also produce heat and stress… not indusive to stability.

On day one, that journeyman (Jim Hahn) took me over to the jointer to make the case. I face jointed and thought it was perfect. The mahogany plank was only 4' long... it jointed beautifully and had no snipe that I could see or feel (but it was there). He "bumped" (that's what they called taking a flattening stroke) the other side flat on the 30" Master. He had been a journeyman 10 years at that point though... he was a master on the sander and didn't need to hinge it; he knew it was flat. We returned to my bench and checked the jointer pass on my surface plate. It was good but not flat. We went back to the sander where he gave me my first lesson on the proper stroke. In one light stroke I could see where it was cleaning up from the jointer. Later, a few other journeymen said they also challenged "flattening on the disc" when they first started in the trade... made me feel better. They claimed that cutting wood flat always releases internal stresses and the wood moves... lightly abrading doesn't as much. Hinging is your final check if you needed it though. Lots to ponder!

[Zachary Hoyt]

I've tried to use the 12" disc sander on my ShopSmith to flatten longer things sometimes. Mostly it's been curly maple banjo necks that I needed to flatten the fretboard surface but the jointer was chipping out too much. I've had mixed results with some necks coming out as good as they would be on the jointer and some requiring several tries to get close enough to be acceptable. One difference is the size of the disc, and also there is no reference surface on the side so there's no support from the table, it's all just handheld. I imagine that if I did it more I might get better at it, but it's only a now and then thing. I have no dust collection on the ShopSmith, and the shaft has a bit of runout, so it's all much more approximate than what you're describing.

[johnny means]

The problem with your example is using the same board for both steps. I'll often face joint a board and it immediately bows. I then joint the bow out and get a perfectly flat face. A better test would be to rip the board in half and apply different techniques to each half. Don't believe anyone who tells you that sanding won't cause cupping or bowing. It's all about the amount of material removed not how you remove it.

[Randy Benway]

I then joint the bow out and get a perfectly flat face.
How do you know that??? Got a coordinate measuring machine? Surface plate? Or just sets flat on your table saw? ;<)

Another lesson important in the pattern shop was humility. You learned it quickly or life with 50 journeymen was brutal. If you remained open to new ideas and learned... you could gain their respect.

[Warren Lake]

how material is removed does in fact effect the end result.

I once asked the old guy why a bevel cut on my saw had more tension release than if i did it on the shaper, there was no pause for an answer. "its because the shaper knife nibbles the material away"

[Mel Fulks]

I think it’s possible that one guy is talking about end grain , and another is on jointing regular boards.

[Steve Demuth]

Not to mention, if you're sanding on a 40 grit disc sander to flatten, you're leaving about 1/100" or more of the board.s surface a ragged mush of cut and torn fibers. I'm not even sure what "flatter" means applied to that kind of surface finish.

[Randy Benway]

I was a journeyman wood patternmaker. With my pattern making cap on... I'm talking about flat vs flat. Just trying to provide some insight into a trade that's long extinct. The big sanders did this job perfectly but it took skill.

Before that I served a 4 year apprenticeship to become a journeyman cabinet maker. I understand your hesitance. Like I stated early in my post "flat to a cabinet maker is NOT the same as flat to a patternmaker." Hardly any woodworker requires this kind of precision... probably even has a hard time comprehending. I am NOT trying to convince you it is required or even important in your work. I just applied the old "flattening stroke" along 4 edges of an end grain cutting board to clean it up. I doubt it is "patternmaker" flat either... don't have a surface plate the hinge it... don't care but it works good and is fast. It is very apparent though that some posters make comments here without direct experience to back it up. Ever run a big disc? Learn to check flatness? Probably not.

I just wanted to illustrate how an old patternmaker might shape up an end grain board.... may or may not be for you. Have fun!

[johnny means]

How do you know that??? Got a coordinate measuring machine? Surface plate? Or just sets flat on your table saw? ;<)

Another lesson important in the pattern shop was humility. You learned it quickly or life with 50 journeymen was brutal. If you remained open to new ideas and learned... you could gain their respect.

Well, I'm not machining engine blocks or cpu coolers, so I wouldn't go to those extremes. I do however have to achieve results that can be fed into a cnc router or laser. Surely, I'm able to get at least as flat as your multifaceted, sanded surface. That still doesn't change the problem with your example which uses a second process to reveal the error in a first process, but never shows the results in reverse.