LumberJocks

puzzling jointer instruction

  • Advertise with us

« back to Power Tools, Hardware and Accessories forum

Forum topic by JeffP posted 05-20-2015 12:28 PM 775 views 0 times favorited 20 replies Add to Favorites Watch
View JeffP's profile

JeffP

573 posts in 857 days


05-20-2015 12:28 PM

Topic tags/keywords: jointer

Yesterday I bought a “toy” jointer (bench top 6 inch porter cable) to hold me over until I have a big boy shop.

I’m reading the instructions right now and was quite puzzled by one unexpected statement. It is in the section describing the size limits of the piece you are jointing.

No big shock…they don’t want you to use the jointer with really “short” pieces (minimum of 10 inches), I assume this is so the piece can be firmly seated on the out feed table before the trailing end gets to the cutter head. Seems reasonable to me.

A little bit less obvious…they don’t want you to use it with particularly “thin” strips, where thin refers to the distance between the tables and the “top” of the piece. In other words, they don’t want you jointing things like edging strips after they have already been cut from a wider board. Makes a little bit of sense for the board to be stiff and to keep your push blocks further away from the knives?

Anyway, the big surprise to me was the third restriction…no boards narrower than 3/4”??? Per the picture, this is referring to the dimension perpendicular to the face of the fence. Like you shouldn’t edge joint a 1/2” thick piece of wood.

Not only does that seem like a significant and unexpected restriction on what i can (should) do with the tool, I also can’t see what safety or cut quality issues would be raised by edge jointing a 1/2” wide or even 1/4” wide piece of stock????

The otherwise reasonably well written instruction booklet offers absolutely no explanation for this restriction. Any ideas?

-- Last week I finally got my $*i# together. Unfortunately, it was in my shop, so I will probably never find it again.


20 replies so far

View Tommy Evans's profile

Tommy Evans

137 posts in 1640 days


#1 posted 05-20-2015 02:03 PM

hmmm, I have no real knowledge for that instruction, but IMHO, it may have to do with the possibility of the narrow board being more prone to shattering and the subsequent dangers. Maybe?

peace, T

View bold1's profile

bold1

262 posts in 1313 days


#2 posted 05-20-2015 02:11 PM

I would think they mean if the board hight would be lower then the fence. 1/2” or 1/4” is hard to hold if it is below fence hight. I’ve run quite a lot of 1/2” on a bench top 4”. Anything narrow below the fence I clamp on a fingerboard to hold it.

View bbasiaga's profile

bbasiaga

757 posts in 1461 days


#3 posted 05-20-2015 02:18 PM

I suspect they are also worried about your hands getting too closer to the blades, guard in place or not. Thin pieces are also less rigid, meaning they could warp from the pressure you are putting down on the table, and the performance of the machine could be compromised – the piece wouldn’t be flat because it was warped differently from the pressure you put on it.

I edge joing 6” wide 3/4” thick or even 1/2” thick boards on every project, using my bench top Shop Fox jointer. No problems.

Does your’s have the ability to shim either the infeed or outfeed table to get them co-planar? Once I set mine up I got great performance out of it. Though the short beds offer some limitations, I have been able to really do some good stuff with this little thing. I think you’ll be pleased.

-Brian

-- Part of engineering is to know when to put your calculator down and pick up your tools.

View JeffP's profile

JeffP

573 posts in 857 days


#4 posted 05-20-2015 02:35 PM

Thanks all.

I suspected that no matter how hard I tried to explain which dimension it was…I wouldn’t be completely successful.

Let’s try an analogy. A 2X4 is about 1.5 by 3 inches. This would be “legal” to either face plane or edge joint on this jointer.

Now, assuming we call flattening the “narrow” edge of that 2X4 “edge jointing” the 2X4…suppose we shrink that sucker down some.

This is ALL about edge jointing it as above.
1) full width of 1.5 inches is “legal”
2) if we cut it in half with a bandsaw such that it becomes a “1X4” (actual size would be about 3/4 X 3.5 minus kerf), it would still be (just) “legal” to edge joint it on this machine
3) now if we take one of those two pieces from 2 above and slice it in half again to get a “1/2 X 4” (which would really be about 3/8 inch thick minus saw kerfs)...it is now too thin to pass their requirements.

So, it is not about the dimension up from the tables and the knives. It is about the dimension out from the face of the fence.

-- Last week I finally got my $*i# together. Unfortunately, it was in my shop, so I will probably never find it again.

View Rob's profile

Rob

704 posts in 2536 days


#5 posted 05-20-2015 02:46 PM

Remember, the people who design tools and write technical manuals are often not woodworkers themselves. I wonder if the second and third prohibitions were mixed up somewhere along the way when they were writing the manual. It would make more sense if they said don’t face joint material less than 3/4” thick, and don’t edge joint really thin pieces.

On the other hand, maybe it’s there more for legal protection—perhaps there’s some evidence to suggest that anything thinner than 3/4” is more likely to shatter if you hit a knot while edge jointing, or that the workpiece doesn’t have enough mass to be held firmly against the fence and you could lose control of it. I know guards in the US are designed so a piece that’s too thin (maybe 1/4”?) will slide under them, but I still think it makes more sense to have the 3/4” minimum thickness restriction on face jointing rather than edge jointing.

-- Ask an expert or be the expert - http://woodworking.stackexchange.com

View Tommy Evans's profile

Tommy Evans

137 posts in 1640 days


#6 posted 05-20-2015 02:48 PM

So, it is not about the dimension up from the tables and the knives. It is about the dimension out from the face of the fence.

- JeffP

yep, that’s why I think it has to do with the (possible) shattering of a brittle wood, especially if you’re jointing “against” the grain. Whether it’s a real possibility is hard to say but they must cover their bases.

View Richard H's profile

Richard H

489 posts in 1146 days


#7 posted 05-20-2015 02:55 PM

I think there is some valid concern about very small pieces shattering or possibly tipping over into the blade on the jointer but I also think the people who write these manuals and their lawyers assume people are going to throw away their push blocks and use their fingers here so they have to at least be able to point to their manual in court and say they tried to prevent this. I don’t have numbers to back it up but several woodworker instructors and commercial people I know have told me the jointer is the most dangerous tool in their shop and I have heard of several 2nd hand accounts of people jointing their finger tips off. I think it ranks up their with the shaper/router if you don’t use a power feeder and the tablesaw just because of the bulk of use at the very least.

There is probably research out their that shows below X dimension the risk of a jointer accident goes up Y precent and those are the numbers that made it into the manual.

The one thing I have experienced with thin pieces is the blade guard gets in the way with push sticks. The temptation is to either remove the guard or use your fingers to move it but both are probably not good ideas. In cases like those I tend to just pull out the jack plane and deal with the piece that way. The manual is a good guide to go by for sure but if a cut feels unsafe it’s best to just stop and look for a better way to do it.

View Rob's profile

Rob

704 posts in 2536 days


#8 posted 05-20-2015 03:04 PM


...

The one thing I have experienced with thin pieces is the blade guard gets in the way with push sticks. The temptation is to either remove the guard or use your fingers to move it but both are probably not good ideas. In cases like those I tend to just pull out the jack plane and deal with the piece that way.

- Richard H

I think most of the US-style guards are designed so a piece that’s too thin will slide under the blade guard. Definitely don’t remove the guard…recently I witnessed an accident in which one of the knives came loose, slammed into the guard, and broke off a chunk of the outfeed table. If the blade guard had been removed, someone would have gone for an ambulance ride.

-- Ask an expert or be the expert - http://woodworking.stackexchange.com

View TheFridge's profile

TheFridge

5765 posts in 952 days


#9 posted 05-20-2015 03:28 PM

If I followed the instructions I couldn’t do half the things I do.

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

View JeffP's profile

JeffP

573 posts in 857 days


#10 posted 05-20-2015 03:35 PM



If I followed the instructions I couldn t do half the things I do.

- TheFridge

Agreed.

But if I understood what bad things might happen when I am edge jointing some 1/4” wide pieces to make a panel out of them, then I would be better prepared to avoid that badness.

For instance, if Tommy is correct and the issue is possibility of shattering dense wood…maybe I would double-sticky tape some wider stock onto it with the edge to be jointed sitting out proud. That way it has more support and something to absorb the vibration etc.

-- Last week I finally got my $*i# together. Unfortunately, it was in my shop, so I will probably never find it again.

View TheFridge's profile

TheFridge

5765 posts in 952 days


#11 posted 05-20-2015 03:40 PM

If it was say 1/4”x 1/2” material, I’d just joint the mother it came from and rip the small piece off.

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

View JeffP's profile

JeffP

573 posts in 857 days


#12 posted 05-20-2015 04:34 PM


If it was say 1/4”x 1/2” material, I d just joint the mother it came from and rip the small piece off.

- TheFridge

nope, i’m talking about edge jointing a 1/4” by 4” piece. (which the instructions say don’t do this)

-- Last week I finally got my $*i# together. Unfortunately, it was in my shop, so I will probably never find it again.

View TheFridge's profile

TheFridge

5765 posts in 952 days


#13 posted 05-20-2015 04:48 PM

Then don’t. Easy.

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

View HornedWoodwork's profile

HornedWoodwork

222 posts in 680 days


#14 posted 05-20-2015 04:59 PM

The 3/4 prohibition is most likely about shattering as others have said. It might also be about “rocking” the board. On a 3/4 inch board you have a decent amount of width to find purchase on the table, but thinner than that the board could rock side to side easier. I imagine it is possible that if you rock the board, one edge could get dragged to the surface which could shatter the board, pull the board (and your hand) aggressively down to the blade, cause kickback, or cause the board to jump dangerously. It could also just muck your cut up really badly.

Imagine cutting the thin part of the board against a very light load, then suddenly and without warning, that load dramatically increases as the board rocks down into the spinning blade exposing more and more surface area, that is the stuff of accidents.

-- Talent, brilliance, and humility are my virtues.

View TheFridge's profile

TheFridge

5765 posts in 952 days


#15 posted 05-20-2015 05:13 PM

If you’re just jointing the edge the face needs to be against the fence right? If they 1’ or shorter I’d just use a table saw.

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

showing 1 through 15 of 20 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com