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Is this a stupid idea?

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Forum topic by patcollins posted 02-20-2017 04:30 PM 709 views 0 times favorited 16 replies Add to Favorites Watch
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patcollins

1605 posts in 2704 days


02-20-2017 04:30 PM

Had just been reading a thread about tearout on a planer and jointer. Someone mentioned a spiral head cutter, but what if someone made a sanding head for a jointer, is that a stupid idea? You could change heads and have a small flatness sander.


16 replies so far

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pintodeluxe

5466 posts in 2652 days


#1 posted 02-20-2017 05:04 PM

In theory it could work. There are small Sand-Flee machines that look very similar to a miniature jointer.

My personal preference is to avoid creating the tearout in the first place.
For instance…

Version 1. Joint and plane with straight knives, some tearout happens, drum sand to remove tearout, ROS to prepare for finish.

Version 2. Joint and plane with helical cutter, virtually no tearout, ROS to prepare for finish.

Basically it helps me skip a step.
In the long run, a helical head (with 4-sided carbide cutters) is actuallt saving me money vs. HSS straight knives.

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

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William Shelley

479 posts in 1308 days


#2 posted 02-20-2017 06:06 PM

I would think for this to work well, the axis of the sanding head/drum would need to be skewed from perpendicular to the direction of stock travel. Otherwise you’d end up with long streaks due to stuff getting lodged in the sandpaper.

The skew angle could be anything from 5 degrees to 45 degrees, I have no idea what would work best.
And would likely need to be skewed so that it pushes the work piece against the fence.

-- Woodworking from an engineer's perspective

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Lazyman

1508 posts in 1226 days


#3 posted 02-20-2017 06:35 PM

Somewhere I have seen a drum sander (might have been homemade) that has a flat surface on the top that you can hand sand on the top of the drum but I don’t think it could easily work in place of a jointer if that is your goal.

Also, making a jointer that you could quickly change the cutterhead to a sanding drum might be as expensive as buying both a jointer and drum sander. It seems to take 30 minutes to an hour to remove and replace the cutterhead in most jointers. Making that simpler would likely require compromises that would mean you wouldn’t want the machine.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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papadan

3584 posts in 3207 days


#4 posted 02-20-2017 06:59 PM



I would think for this to work well, the axis of the sanding head/drum would need to be skewed from perpendicular to the direction of stock travel. Otherwise you d end up with long streaks due to stuff getting lodged in the sandpaper.

The skew angle could be anything from 5 degrees to 45 degrees, I have no idea what would work best.
And would likely need to be skewed so that it pushes the work piece against the fence.

- William Shelley


By all rights, any jointer or planer should work better with the cutter head skewed slightly. 5 degrees would make a big difference in performance. It would eliminate snipe for one thing having the blades start the cut at a corner of the board and work across to full cut as the wood progresses and exiting the cutter also. That’s how the helical heads work! Why not skew the straight blade cutter heads?

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gwilki

170 posts in 1313 days


#5 posted 02-20-2017 07:40 PM

If you search on “drum sander plans”, you will see many free plans to make a drum sander. That would be, in effect, your jointer with a sanding head. Swapping out a jointer head for a sanding drum would not be very practical IMHO.

I’m with Papadan on skewing while jointing. I can’t skew my jointer head, obviously, but I can skew the board that I’m jointing. I do that every time the board that I’m jointing is narrow enough to allow me to skew on the jointer bed.

-- Grant Wilkinson, Ottawa ON

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Lazyman

1508 posts in 1226 days


#6 posted 02-20-2017 08:23 PM


I m with Papadan on skewing while jointing. I can t skew my jointer head, obviously, but I can skew the board that I m jointing. I do that every time the board that I m jointing is narrow enough to allow me to skew on the jointer bed.

- gwilki

Hmm? Seems like someone would have made a jointer with a skewed head by now if that was a good idea. It seems to me that the only place that really makes a difference is on the leading and trailing edges. For the rest of the pass, the blade is always in full contact which is very different than how a helical or spiral head works. In fact, by skewing the wood (or the head) wouldn’t you actually be in affect presenting a wider cross section diagonally and thereby making the pass more difficult? And with the blades continually exiting along the side skewed towards the backside, is there a chance of more tearout along that edge?

I can’t quite wrap my mind around how a skewed approach with a traditional cutter head would lead to a cleaner cut?

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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TheFridge

8333 posts in 1325 days


#7 posted 02-20-2017 08:30 PM

Id think a sanding drum would need constant replacement.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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AZWoody

1138 posts in 1063 days


#8 posted 02-20-2017 08:32 PM

I believe Woodmaster makes a planer with interchangeable heads that do just that.

The challenge of retrofitting something that’s not designed for that is you have to get the tolerances pretty tight or each time you change you have to readjust the feed rollers to work properly in relation to whichever head you have installed. If not, you have the possibility of shooting boards back at you.

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Loren

9633 posts in 3487 days


#9 posted 02-20-2017 09:16 PM

Such machines have been made… I read
about a guy on practical machinest (I think
its the fellow who arguably makes the
world’s finest hand planes) who has a
machine with a sanding head and iron
jointer tables.

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gwilki

170 posts in 1313 days


#10 posted 02-21-2017 03:08 PM

Lazyman: I don’t know if someone would have made a skewed head jointer if skewing the piece is a good idea or not. However, skewing the piece means that the blades are cutting the grain at an angle – not straight on and I find that sometimes that gives me a better finish. It’s the same principle, I think, as when I use a skew chisel turning. The edge of the chisel is skewed to the grain giving a better finish.

You are correct, of course, that more of the width is being cut. Maybe that’s why no one manufactures a skewed-head jointer. For a 6” wide jointer bed, you would need a 7 or 8 or longer head = more money. :-)

-- Grant Wilkinson, Ottawa ON

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Greg the Cajun Wood Artist

381 posts in 781 days


#11 posted 02-21-2017 04:25 PM

Motor speed might be an isssue

-- Wood for projects is like a good Fart..."better when you cut it yourself"

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Mark Shymanski

5621 posts in 3552 days


#12 posted 02-21-2017 04:27 PM

If it starts out with “Here hold my beer…” then you can almost guarantee it is a stupid idea. :-)

Could you work out a prototype and see how that worked and then go from there?

-- "Checking for square? What madness is this! The cabinet is square because I will it to be so!" Jeremy Greiner LJ Topic#20953 2011 Feb 2

View Lazyman's profile

Lazyman

1508 posts in 1226 days


#13 posted 02-21-2017 10:38 PM



Lazyman: I don t know if someone would have made a skewed head jointer if skewing the piece is a good idea or not. However, skewing the piece means that the blades are cutting the grain at an angle – not straight on and I find that sometimes that gives me a better finish. It s the same principle, I think, as when I use a skew chisel turning. The edge of the chisel is skewed to the grain giving a better finish.

- gwilki

I am just a few steps above novice when it comes to turning but my assumption on the skew chisel was always that the reason to skew it was to avoid catching the edge. By presenting the edge at that angle, you are typically only using a small section of the skew chisel’s edge at any given time which seems a little like the opposite affect but I get your drift. When using a hand chisel it is often easier to pare at an angle to the grain with a slicing action which is similar, at least in my mind, to how a spiral cutter head works. I am just having a hard time getting my mind to imagine how that would help while using a standard cutter head because the entire edge of the blade still contacts all at once. But this wouldn’t be the first time my imagination has failed me! I will have to experiment with that next time I have some difficult grain to see if I can detect any differences, though with my 6” jointer I won[t be able to skew the piece much.

Thanks for the explanation.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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RobS888

2316 posts in 1684 days


#14 posted 02-22-2017 04:13 AM

My jet jointer/planer manual says the cutter head spins at 5,500rpm. I could find that drum sanders run in the 1,400 to 2,500 rpm range. That seems way too fast for sanding.

-- I always suspected many gun nuts were afraid of something, just never thought popcorn was on the list.

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patcollins

1605 posts in 2704 days


#15 posted 02-22-2017 04:22 AM



My jet jointer/planer manual says the cutter head spins at 5,500rpm. I could find that drum sanders run in the 1,400 to 2,500 rpm range. That seems way too fast for sanding.

- RobS888

I would think that could easily be taken care of with a step pully system.

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