Gluing after drum sanding?

[Yuri Strukov]

Hello, I was wondering about what would make a better face gluing surface,
running a board through a planer or through a drum sander?
I have seen many suggest using a planer first and then finish the
board with a 120-180 grit drum sander for face glue-ups. My questions are:
Wouldn't a 180 grit sanding be too coarse for gluing and why sand an
already planted surface, which is supposed to be as smooth as one can go?

Would appreciate any feedback and comment!
Thank you and Best wishes,
YS

[Mel Fulks]

Most planers get some nicks in the knives pretty fast , some are big , they can make for an ugly edge. For gluing two surfaces together,
I just wrap some sandpaper around a piece of scrap and sand quickly across grain to remove the “humps “ , that makes for a thin as
possible glue line.

[Randy Heinemann]

I would think the surface from a drum sander with 120 grit would give a great gluing surface. After all plywood like Baltic birch is sanded to 120 grit off the shelf. However a jointed edge is also gives a solid, strong joint.

[Zachary Hoyt]

I use 80 grit on the disc sander and drum sander for all surfaces, including those to be glued. I also glue right off the jointer or planer. Both types of surface seem to glue just fine.

[Yuri Strukov]

Appreciate all the responses and thanks for sharing the tips! I will experiment with manual sanding with high grit after planing and running through 180 grit on the drum sander for face gluing. I've had an impression that for glues like Titebond, the smoother the surface, the stronger the lamination. For edge gluing, I always lightly finish the edges with a low-angle hand plane for invisible (also the strongest?) glue lines. Good to know 80 and 120 grit sanding still acceptable for gluing. Best, ys

[John TenEyck]

The drum sander always gives a flat, clean-cut surface, which allows the glue to penetrate for a good bond. All planer knives will leave a scallop and dull ones will compress the wood; neither is great for a good bond. If you want to face glue after only planing, make sure the knives are sharp. Hand sanding or a light pass with the ROS is a good idea, too. Purists would hand plane the surfaces.

John

[Richard Coers]

Depends on the drum sander, but I find 180 grit to be a problem. You have to take incredibly light cuts and it's easy to fill the abrasive with some species of wood. It's very rare that I use anything other than 120 grit.

[Bill Howatt]

FWIW:
While this isn't gluing, when staining the exterior of a house for example, the advice is to sand to remove mill glaze which is the result of machine planning so the finish penetrates better.

[John TenEyck]

Depends on the drum sander, but I find 180 grit to be a problem. You have to take incredibly light cuts and it's easy to fill the abrasive with some species of wood. It's very rare that I use anything other than 120 grit.

I agree. I use 80 grit on both drums, or 80 then 100 grit on the second. Anything beyond 120 grit is interminably slow and subject to burning, etc., as you said. I know some folks use 220 grit on their DS, but I don't have the patience. I find my ROS to be the better option for finer grits.

John

[Yuri Strukov]

Thanks for all the responses! It's just that I have never glued up sanded surfaces, and never thought as coarse as grit 120 would even work. Don't PBA-based glues require a planed surface for the glues to work properly through forming a molecular bond?

[Carl Beckett]

This may not be a useful comment, but I have glued all kinds of surfaces that were less than ideal. I can not recall a structural failure, although I do at times have 'gaps' if a board isnt 'flat'.

[Mick Simon]

I've glued straight off of the drum sander with 120 grit for years and never had a failure, including multi-layer bent laminations. I find it's best practice to blow off or vacuum the surface well to get rid of the dust.

[Zachary Hoyt]

I use the drum sander or the planer to flatten lumber and then cut neck sections out of the boards and glue them together. I have not had any trouble with either 80 grit off the drum sander or off the planer. These are critical joints and no "glue line" is tolerated, and I have found that both methods work equally fine. What matters for me is that the wood is flat, and to use plenty of clamps and enough glue for squeezeout all around.

[Kevin Jenness]

As long as the surfaces are flat and cleanly cut a machine planed surface is fine for most wood glues. Snipe, obvious knife nicks and dull knives can cause a problem. Old or glazed surfaces benefit from sanding. Epoxy is one exception that works better with sanded or sawn surfaces and can tolerate a thick glueline.

[Steve Demuth]

I stick to 80 grit on my drum sander for the most part, and use a hand sander if I need to go finer than that. But when I do use finer grits on the drum sander, I spray them with teflon spray frequently. Improves release of the dust and reduces the tendency to burn by a great deal.

[Randy Heinemann]

Based on experience with Performax 16-32 I wouldn’t go beyond 120. Even that is probably a higher grit than necessary. Sanding with finer grits on a drum sander is difficult and requires only extremely light passes; as light as possible. Remember that the job of a drum sander is to flatten the surface it does a great job of that. For gluing, a flat surface is the highest priority.

[Yuri Strukov]

For gluing, a flat surface is the highest priority.

Thanks Randy. It's just that I always shoot for invisible glue lines both for looks and for structural integrity and was wondering if 80 or even 120 could give a glue line as thin as for planed surfaces.

[Zachary Hoyt]

I can see no difference between planed and 80 grit sanded, both are invisible if flat.

[Maurice Mcmurry]

What Zach says is my experience as well. I use a light table to check the fit for my glue ups. The final fitting almost always comes down to a small block plane and an abrasive shooting board. Occasionally the fit is OK right off of the table saw. Occasionally it is OK right off of the jointer or planer. How well the pieces fit together is my only concern. What was used to create the surface make no difference as far as I can tell. The surface does need to be smooth. 60 grit is as corse as I go on the abrasive. A table saw or jointer surface that creates a light proof joint is a rare thing. It can be done. I am no good at getting a perfect joint with a big hand plane.

[Warren Lake]

thin glue lines mean nothing if your material selection is not done in a way that the boards are not the same or close. The glue line may not show if thin but the boards that are different or joined on different grain will show that two different boards are joined together. Type of glue will make a difference some white glues will leave a black glue line depending on the wood colour and tannins.

What are you gluing together Yuri, edges or faces? I don't know a cabinet maker who runs things through a drum sander before gluing. If you have a jointer and planer thats all you need.

[George Yetka]

I think everyones setup will be different. I run 100 in my drum sander. The final product has a definite texture. I then sand with Rotex 80 grit to get those out, Rotex 120, RO 120, and on. My planer gives a very nice 120 grit ro equivelant surface or better. So I would prefer gluing off of my planer. If your jointer/planer leaves tearout and you drum sand at 220 you may prefer drum sander

[Randy Heinemann]

Try some small boards and see if the result is satisfactory for you. I never use anything finer than 120 on my drum sander; and most often 100. It light be OK to use finer for a final pass where you would take off the tiniest amount of wood. The purpose of a drum sander is to flatten not to finish sand.

[Jonathan Jung]

I'm with Zach

[Yuri Strukov]

What are you gluing together Yuri, edges or faces? I don't know a cabinet maker who runs things through a drum sander before gluing. If you have a jointer and planer thats all you need.

Warren, thanks for the response! I am joining two faces of identical wood/grain that are wider than the 6" jointer, and was wondering if a drum sander at 120 grit would give a surface good enough for Titebond.

Someone said that the planer might not give a surface much smoother than 120 grit. Yes, I have to try and see what the glue line is.

[Warren Lake]

There is no reason to run stuff through a sander before you glue it off the planer. Knew some of the best cabinetmakers around till they passed and not one of them would do that.

[Yuri Strukov]

There is no reason to run stuff through a sander before you glue it off the planer. Knew some of the best cabinetmakers around till they passed and not one of them would do that.

Makes sense! What would they do when the panels were wider than the planer could run? I can think of smoothing it with a jointer hand plane or with a long fine grit sanding block.

[Warren Lake]

Up above you talk six inches wide and i guess you are gluing up for more thickness. Drum sander is not the machine they are calibrating machines at best. They are not going to joint your material and make it flat. Find someone with a jointer and joint it and plane it parallel and glue them together.