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Rough Milling - - HELP!

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Forum topic by rbterhune posted 1310 days ago 1050 views 0 times favorited 10 replies Add to Favorites Watch
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rbterhune

171 posts in 1827 days


1310 days ago

Topic tags/keywords: question poplar

I just finished rough milling some poplar for my 1st project…both 4/4 and 5/4.

As suggested by many on this forum, I took my stock down to about 1/16th to 1/8th oversize. My obvious intention was to come back for a finish milling.

I have big problem however…my rough milled stock is bowing along its lenth before I can even get it set aside and sticker. This is so much so that I’m not sure I’ll get the thickness I need upon finish milling. I’m fairly certain this may be a release of tension rather than moisture, given that it happens within 20-30 minutes (almost immediately) of face jointing the first side.

It seems as though it’s only happening to the 5/4 stock…the 4/4 is o.k.

I’m using a planer sled and to face joint the 1st side, as I don’t have a jointer. My sled is doubled up 1/2” MDF and I am being careful to shim properly, as I know many of you are already thinking of this. Also, concave side is up to minimize material loss.

1st, what are your general thoughts?

2nd, what do you think about stacking without stickers and applying weight to flatten the boards over the coming week?

Thanks,

Brad


10 replies so far

View Loren's profile

Loren

7284 posts in 2253 days


#1 posted 1310 days ago

I rough mill just to get a look at the board – then lean the boards
against a wall for a day or two. Then come back and look at the
boards and see what you’ve got: where the twisting is, which
boards seem inclined to mill up straight and so forth.

Then mill your favorites down a bit and lean them against the wall
again for a day. You can crosscut or otherwise cut down
boards that are obviously not going to be straight their whole
length.

Of course you try to make good choices when you buy the wood in
the first place, but you really have to study the wood in the end
and use each piece appropriately.

Milling for maximum yield in furnituremaking is a study. I’ve found
chalk and a 78” level to be the most useful tools for milling rough lumber.
You get so you can eyeball the twisting but the level helps you identify
those long pieces that are best for big doors, table-tops and so forth.

I don’t think trying to force wood to go straight with weights is
likely to help you get straight boards.

-- http://lawoodworking.com

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rbterhune

171 posts in 1827 days


#2 posted 1310 days ago

Great tips…the bummer about it all is that I’ve almost gone through the extra 5/4 board I got. Any more bowed/cupped boards and I need a new trip to the lumberyard…sucks.

View ChrisCarr's profile

ChrisCarr

196 posts in 1504 days


#3 posted 1310 days ago

Did you plane the other side after your did the first side? taking material off one side but not another will give stress to the board.

Is your lumber properly dried?

If you are attaching the board to a support thicker than it in your project it could pull the bow out. I wouldn’t count on hoping for this as it doesn’t always work if your not using screws.

View PurpLev's profile

PurpLev

8476 posts in 2254 days


#4 posted 1309 days ago

There are several things that might be going on here.

1. your jointing operation may not have surfaced an existing cup flat (not saying it didn’t but from not knowing better this would be an option)

2. “concave side up to minimize material loss” ?!? if you are trying to remove a bow from a board to get it flat, it does not matter which side is up as long as you remove that bow. When using a jointer it is important to keep the convex side up not for material gain but for stability on the tables (trying to joint a rocking chair is practically insane)

3. I assume you have milled both sides of the boards, but since you did not mention it in your post – if you haven’t, than that would create uneveness in the boards which will make them deform

4. Since this is only happening with the stack of 5/4 it may indicate that it came from a batch of boards with internal stresses, or improperly dried lumber – personally I would tend to think this is the most logical issue here since your 4/4 stack which was milled the same way did not seem to bow

5. the only ‘real’ way to bend wood back is to steam bend it – you’d have to make it plyable, then fix it in some fixture to counter the bow, this is not perfect though as it could create a bow the other way, or not ‘pull’ it completely straight…

-- ㊍ When in doubt - There is no doubt - Go the safer route.

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cabmaker

1292 posts in 1415 days


#5 posted 1309 days ago

For what its worth to you: Don t do anything to your material until its acclimated. Thats typically not a problem if your buying from shed stored lumber and going straight to a like type environment (shop). Another important thing is do not cut your stock up into short lengths to soon unless neccessary to handle, stck or whatever. Was your material KD,air dried or what.JB

View Loren's profile

Loren

7284 posts in 2253 days


#6 posted 1309 days ago

Sometimes the best tactic for a board is to crosscut out the cupped or twisted
parts (which can be most of it) and then rip those parts in half.

I haven’t worked with rough poplar in awhile but if memory serves, it’s not
very easy to mill true. Alder is better but not as cheap anymore for paint
grade work.

-- http://lawoodworking.com

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rbterhune

171 posts in 1827 days


#7 posted 1309 days ago

Purplev and others…yes, I planed both sides…roughly equal amounts.

cabmaker…the material was KD.

Loren…I have already crosscut my lumber to a long rough length.

What Loren says about poplar being tough to mill true…have others experienced this problem?

View tnwood's profile

tnwood

195 posts in 1692 days


#8 posted 1309 days ago

I think your 5/4 stock was case hardened in the kiln. If so, there really is nothing you can do about it. I’ve run into it with various outlets before. I’m not sure but I think the problem relates to either heating it too rapidly or too high or maybe both. I had a large quantity of hard maple several years ago that I bought from a sawmill in NH. The only way to use it was to rip it on a bandsaw as it move on me even with a splitter on the table saw. I finally used it in short pieces inside a cabinet as it was impossible to use at even normal 3-4’ lengths. I never bought anything else from that mill. In all fairness, they didn’t have a kiln so they either bought it from someone or contracted for kiln drying. Nevertheless, it was sloppy work and they should have dealt with it.

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rbterhune

171 posts in 1827 days


#9 posted 1309 days ago

tnwood…your name implies you’re from Tennessee…I am in the Nashville area and purchased the lumber from Summers Lumber. Know anything about them?

You may have the correct assessment. After some research on case hardening I found that the stresses will be relieved immediately. Once person even side the wood was pinching his blade WITH a splitter…I had a couple of pieces do that exact same thing.

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tnwood

195 posts in 1692 days


#10 posted 1309 days ago

rbterhune – I’m located in Maryville, just south of Knoxville. I don’t know Summer Lumber. The closest commercial hardwood supplier here is Jefferies in south Knoxville. I’ve only bought ply and small stuff from them so far. They have a pretty good variety but are somewhat pricey. I relocated here from NH a little over a year ago and brought several hundred bf of cherry, maple, walnut and a bit of oak with me. All the cherry and maple I milled from my woodlot in NH using a little hand held bandsaw mill powered with a chainsaw head. I had bought the problem maple before I had the stuff I milled was dry as I didn’t have a kiln and was air drying and hard maple takes a long time to air dry. I bought curly maple from the same dealer at the same time and it was not case hardened which leads me to believe the dealer bought the hard maple from someone else. I’ve had the same problem with occasional boards of various species from other sources but never a large quantity. Some time ago, the following link gave a lot of information about TN hardwood suppliers. http://lumberjocks.com/topics/22097#reply-229796 This might of of value to you.

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