Help there must be an answer

[engineer one]

my brain hurts #-o ](*,)

like so many things that have been around for years,
like windowcills on windows. practice in the 60' and 70's was to
remove them, which is why so many of those buildings
have rain stains under every window. :lol: :twisted:

i think one of the major reasons that electric p/t's have adjustable tables
is that the wood has a tendency to lift as it goes over the blades that
rotate. it is i think one of the reasons for snipe,
one of the reasons people like me find hand held electric planes
difficult to use(thank goodness), and every room door i have done
electrically recently has a hollow at one end or the other.

even with a good push block, and downward pressure where ever you can,
the wood passing either over or under the cutter heads are going to
tend to lift or dip because of the way in which the cutter block
rotates. i wonder whether spiral blades work any better than straight???

however, with a hand plane, the cutting motion involves weight transfer
but basically a constant downward pressure on the cutting area. pushing down the front at the beginning, or the tail at the end, does not change the weight in the middle too much, thus having made the initial cut,
with the weight on the front tote.

then in the middle of the cut, the weight is equally centred about the
blade, then at the end, to stop the plane tilting over the edge, you push down on the rear.

so you flatten the wood in front before the cut starts, then as you cut,
because of weight transfer the front tilts up in a miniscule way, and
the tail rides on the piece behind which has been flattened, so automatically
the plane adjusts itself without the need for moveable platens, since there
is really no rotating grab like on a p/t.

when you start on a rough piece of timber, you are going to initially get uneven shavings i think, and so far have experienced, then as it gets
flatter, and you are happier with the grain pattern, the shavings should
if we have sharpened properly become longer, albiet thinner.

so from an engineering point of view (sorry alf i slipped back into the thought process ) once you have started to produce thin shavings,
i reckon the minute angle of attack in front of the blade where the sole
rests on the uncut wood gives you the same thing as the adjustable out feed table on the electric jobbies.

sorry if the is only 2 pence worth feels like it is so much waffle that it ought to be worth more :lol: :lol: :lol: :lol:

like these long ones where we seem to go from knowledge to theory
back to personal experience, to ??????????????

paul :wink:

 

[Scrit]

I think one of the major reasons that electric p/t's have adjustable tables is that the wood has a tendency to lift as it goes over the blades that rotate. It is I think one of the reasons for snipe

Overhand planers have adjustable infeed tables (and in the case of industrial stuff like mine outfeeds are also adjustable), but the cutting action on overhand (machine) planing is a downcut action which if anything pulls the work downwards onto the infeed table - and if you think that a 12 x 3in iroko plank 16 ft long is lifted by the cutters - the answer is only if they're blunt!

With machine planing pressure is applied on the infeed side of the machine until a large enough register surface has been created on the planed timber at which time pressure is then applied to the outfeed and the outfeed table becomes your register surface. If you are getting snipe at this point then your outfeed table is set too low relative to the cutters. This motion is actually analogous to the pressure at the front of the plane at the beginning of the cut/rear of the plane for the rest of the cut used with hand planes.

Thicknessers employ pressure bars and feeder rollers (in lightweight equipment they are one and the same thing) so if the pressure springs are properly set-up you'll get little or no lifting of the timber in the middle of the cut because the pressure bars will keep it firmly planted on the thicknesser table so long as both of them are in contact with the timber. Snipe in a thicknesser is a combination of things - in the main it's down to the work dropping as it exits the machine or being lifted as it enters - note that at these points the work is not being restrained by two pressure bars/feed rollers only one. In addition thicknessing being an upcut action which will tend to lift the workpiece at this time of reduced support. If thicknessers were designed with a pair of pressure bars on the infeed and outfeed sides you would circumvent this - the proof comes again from modern 4-sided planers which don't normally snipe - because they have multiple feed rollers on the infeed and outfeed ends which act as a sort of multiple pressure bar. A simple cure for snipe is to feed a piece of scrap stock through the thicknesser butted up to the end of your piece - that way the snipe is on the scrap piece. Another way to reduce it is the lengthen the infeed and outfeed supports - something Felder and Aigner both address with their table extenders.

On very low cost and portable thicknessers the snipe issue can be exacerbated by the design of the cutterhead/feed roller set which on some models allows the head to lift or drop slightly (it is actually pivoting) at the start/end of the cut and so accentuates the snipe.

An interesting aside to the issue of overhand planers is that it is sometimes necessary to adjust the height of the outfeed table (relative to the cutters)to accommodate different species (and keep the snipe to a minimum). I put this down to compression and springback of the fibres during the cutting process of planing varying from species to species.

... one of the reasons people like me find hand held electric planes difficult to use (thank goodness), and every room door I have done electrically recently has a hollow at one end or the other.

In that case your technique is possibly at fault and the setting of your planer may also be amiss. The fibre spring back may be one part of your problem, but a far greater problem is possibly how you hold the tool. Downwards pressure needs to be applied to the nose of the planer at the start of the cut, but transferred to the main body of the cut as soon as you have a sufficiently long register surface to ride the main part of the sole along. I'm not saying you'll get no snipe, but you should get much less if you handle the plane this way. This is the "classic" way to handle a hand plane, too.

I wonder whether spiral blades work any better than straight???

Spirals give you a smoother surface cut with less noticeable "ripple" effect probably because the knife enters the cut into the timber more gradually with a shearing action rather than all at once, which does induce some vibration in the timber. optically it may also be that the effect of a diagonal ripple is less noticeable than that of a right angle one. Going to a 4-blade block has a similar effect to using spirals as the size of the "bite" or scallop is reduced for a given depth of cut at a given feed speed - although obviously not quite as good as a 4 cutter spiral it is a much cheaper solution to implement from a manufacturing point of view. Another thing which make the scallop less noticeable ir the size of the cutterblock. A 4 to 5in diameter block, as found on larger machines will produce a shallower scallop that the 2in diameter blocks found on some smaller machines. It is interesting to note that large industrial 4-sided planers, like the Weinigs, employ 6, 8 or even 12 knives (or more) on blocks up to 10 or 12in in diameter to give smoother finishes at high feed speeds.

Scrit

 

[newt]

Thanks Alf for the link. For those that are interested it does discuss the issue relating to why the whole of the sole cannot be in contact with the wood during planning. However there is a possible answer as to why it works. The questionable logic in my original post did not consider the compressibility of the wood or any deflection of the planes sole. Both occur in a dynamic situation which goes some way (perhaps all the way) in explaining why a hand plane can plane a surface flat. There is also some comprehensive posts on snipe from Scrit and Engineer one. Thanks everyone hope the subject was not to boring.

 

[engineer one]

as usual scrit i have learnt even more than you have forgotten,
so thanks. i think my power hand plane technique is one of
fear, i actually do not like using the damn thing which is why i
guess i get the snipe.

apart from the time scale, i would have preferred to cut the bottom
of the doors by hand, and actually find the rali brand plane a good
site item if it is a small amount to be removed,
it was when i fitted a new door over a new floor that i found the
need for the power plane. i think it is something to do with the
balance, so you are right scrit my technique needs improving,
but i'd rather learn to plane by my LV.LN and nooitgedagt ones
properly, at least i can practice for a couple of minutes at a time,
and not produce anywhere as much dust to chase another thread.

paul :wink:

 

[devonwoody]

Remember hand planing is only sophisticated carving.

 

[Anonymous]

You must enter a message when posting

 

[Inspector]

Newt

"In my second post I asked if a hand plane with an adjustable front shoe which would set the depth of cut, thus providing intimate contact for both the in-feed and out-feed during the planning process, would work. If there is genuine support for this idea I may have a go at making a prototype."

Rather than expending a great deal of effort making a prototype, why don't you take one of your planes and glue on some brass shim stock (or a piece of pop/beer can) with some kind of dissolvable glue on the back of the sole? Then after you find out if there is/isn't an improvement you can take off the shim and decide if it's worth developing further.

 

[engineer one]

at last we are back to the right way to experiment,
beer can in one hand whilst contemplating the next step. :lol:

i think the best plan is to soberly practice your normal planing,
and save the beer for relaxation. ccasion5:

paul :wink:

 

[Scrit]

In my second post I asked if a hand plane with an adjustable front shoe which would set the depth of cut, thus providing intimate contact for both the in-feed and out-feed during the planning process, would work. If there is genuine support for this idea I may have a go at making a prototype.

Well, isn't this EXACTLY how a (hand) power planer works? The nose moves up and down to adjust thwe dwpth of cut. If you're into antique planes you'll find that the Stanley #72 chamfer plane

can be set-up to cut that way, too. Save the brass for inlay - go play with yer Bosch/deWalt/Makita..... :wink:

Scrit

 

[Anonymous]

You must enter a message when posting

 

[Shady]

I knew this rang some bells - here's a link to an interesting experiment:

http://www.amgron.clara.net/planingpoints/bodydeflection/deflectionindex.htm

It's by Jeff Gorman. As Alf observed, not a new topic - but an interesting one...

 

[Sgian Dubh]

Shady, I recently said in a discussion on the, for me, rarely visited hand tool side that I reckon I can bend the sole of a try or jointer plane whilst taking a shaving and I use the technique for straightening edges for edge joinery. How believable other users find this claim, I can't say. I do demonstrate the technique to learners I deal with-- and they seem to believe it. They look at the shavings to detect the difference in their thickness along their length-- unscientific I know but it seems to convince.

I'm not sure how relevant plane sole bending is to this discussion overall, but there it is.

I do know I can use planes well enough to do what I want to do. I try to maintain a simplistic sharp'n'go philosophy when it comes to planes. It saves a lot of brain ache. Slainte.

 

[newt]

Scrit,
I shall not be making a prototype, thanks for the info.

 

[sonofnewt]

Interesting discussion.

How much of a hand planes effect is based on opening up a 'plane' - for want of a better term and avoidance of a pun' between layers in the wood?

In other words, once you have engaged the blade and started the cut, if your technique is good would the blade follow the natural plane between wood layers? That way the relative differences in depth across the sole plate would not be too important, although low friction would be to prevent binding and snagging.

For this to be true, hand planes would be more effective in softer woods with more distinct tissue planes for the blade to follow. Is this the case?

 

[Philly]

Hi Sonofnewt
Any relation?
A handplane avoids (hopefully) the effect you describe by having a "mouth". The sole ahead of the iron and the size of the mouth forces the cut. If you used a drawknife you could follow the natural path of the timber. Also if you used a chisel freehand it would want to follow the grain.
A hand plane allows you to make a "plane" where YOU want, not where the wood wants.
Hope this makes sense,
Philly

 

[Newbie_Neil]

Hi sonofnewt

Welcome to the forum.

Cheers
Neil

 

[ivan]

Once the whole length of the handplane is on the wood (assumed already flat for this eg.) and cutting a continuous shaving, isn't it running on the front edge of the mouth (just in front of the blade and where wood planes wear) and the rear end? Some japanese planes have the sole relieved behind the mouth, as this bit is not supposed to be doing any work.