Unreasonable expectations??

[Neil]

The fence itself is an aluminium extrusion much like on almost every other machine in this class

Why do most P/Ts have aluminium fences, even the ones at this budget (and beyond - don't the Rojeks have them too?). It seems bizarre to me when even very low-end dedicated planers have cast iron fences. Would a cast-iron fence be too heavy to remove on a regular basis when converting to thicknesser mode?

Its one of the main reasons I decided to go down the separates route - I've lost count of the number of posts I've read with complaints about aluminium fences.

Cheers,
Neil

 

[WellsWood]

Why do most P/Ts have aluminium fences, even the ones at this budget (and beyond - don't the Rojeks have them too?). Cheers,
Neil

Beats me! Can only be cost, but it seems a strange place to cut corners to me. I'll be asking Nick when we speak, maybe he knows.
Yes the Rojeks do, but it's a much more robust extrusion and triangular in section and therefore stiffer. However one of the reasons I chose the Jet was I thought it had a better support mechanism with regard to stability and ease of fettling.

Mark

 

[engineer one]

ok mark, strangely i do understand what you are complaining about, but i just think that you are wrong about your conclusions.

this is what i do on my little machine. take a number of thin cuts for the
face side, check for break out make sure that i have my grain direction
correctly.

then frankly with a flat face, i put the edge through the table saw,
particularly if it is not giving the impression of being approximately
square.

then i put it through the planer vertically against the fence. now my instinct
is to push it against the bottom of the fence, since i "know " that bit is
square to the table.

the middle of the fence is to my mind irrelevant to the square edge.

maybe my way of working is not proper, but it does work, and
if my edge planing is of a small increment the pressure needed to
keep the bottom against the fence bottom is very low .

hope this makes sense too

paul :wink:

 

[RogerS]

Maybe they all get them from the same *duff* manufacturer of cheapie cast aluminium fences?

 

[engineer one]

maybe the extrusion is not properly scaled in the middle, and when
the fence cooled down after extruding it bowed slightly.

that is why so many aluminium tools seem overly full of webs
in the centre, to stop post manufacture movement.

still not convinced that it is as difficult to deal with as suggested,
but i await the words of wisdom from jetman to see whether
he feels it is as much of a problem as it seems
paul :wink:

 

[-David-]

Just to chip in here -

Now, I do not know what the cross section of the fence looks like, but judging by the rough scale of the piece there should be no distortion. The extrusion die would have been manufactured to within very tight tolerences, the fault then would be either in the die design or the manufacturing process. The die maker should have dimensioned the cross sectional elements to negate any differential cooling and therefore distortion. My guess is that the fault is shared between too small a wall thickness (cost saving) , too fast an extrusion feed rate (cost saving) and no monitored cooling (cost saving).

It can be not much better with cast iron castings. We would think that a machined surface should be perfect, but often, as with my SIP cast fence they are certainly not. Post casting care is just as much an art as the casting process itself. I wonder how many manufactures - cast / rough machine / heat treat to get rid of internal stresses / final machining ?
As a cost cutting exercise the after casting care would be the first to go.


David

 

[WellsWood]

OK folks, for those sceptics out there I've just done a proper controlled test for "actual" results. It went like this:

I took a 600mm length of 140mm x 25mm Maple and, after carefully setting the fence square to the table with a 250mm engineers square, I surface planed the face side (the 140mm face)
I then put that face against the fence and put a face edge on the board. The result? - a perfect square edge to the board as checked with the same engineers square used to set the fence.
Next, I ripped the board to 70mm wide on the band saw.
Back to the Jet, I re-planed the (now 70mm) face side to remove any possibility of movement after ripping.
Finally I replaned the face edge, without changing any settings whatsoever, and having re-checked the squareness of the fence to the table, and being sure to pass the timber in the same direction. The only difference being that this time the face side aginst the fence was only 70mm wide.
The result? a board whose face and edge were clearly not square to each other. I didn't even need to raise the peice to the light to see the daylight pouring between one side of the face and the blade of the square.

I am aware that as most of us have had little or no formal training in woodworking, and I am no exception to this, and work in different ways. But I fail to see how any attempt to plane an edge on a board that is square to the face without using the face as a reference is likely to be reliable. This is after all the fundamental principle of how the "old fashioned" (apologies to all you LN owners) method of using shooting board works (as I understand it at least): The face side sits on a surface that is exactly parallel to that which the side of the plane sits, the side of the plane is square to the sole (and therefore the blade if properly set) and produces an edge that is square to the face.

I wonder how many manufactures - cast / rough machine / heat treat to get rid of internal stresses / final machining ?
As a cost cutting exercise the after casting care would be the first to go.


David

David, I hope you had hold of a good big chunk of wood when you said that. I'd be lying if I said that thought hadn't been going round the back of my head for a while now.


Oh well, must get on.
Mark[/i]

 

[engineer one]

ok mark, that is a fair test, and seems to answer the question in
a way that i did not think it would. thanks for taking the trouble
to do so.

i do understand your analogy about the shooting board, i just
did not think that by pressing into the bottom of the fence
you would have the need the middle to be as flat. i guess it
does to some extent depend upon how you keep the
pressure up along the whole length.

sorry if i caused you any inconvenience with my maybe dumb
suggestions,but at least now we all know.

as for what dave says, since no one, except lv and ln seem to
"age" their castings at all these days it will always be some kind
of problem. maybe jet will need to do better post delivery quality control.

i am glad you feel that both jet and axminster are rising to the plate,
and i certainly felt that from your comments. just a shame they
have to. still look at it another way, you have to fettle your
hand plane :lol: :twisted: :lol:

paul :wink:
ps will try on my machine to see whether i can replicate the problem.

 

[WellsWood]

To be fair Paul I did the test mostly for my own satisfacton, but you're welcome anyway. This forum about nothing unless it is the sharing of views in order that we can all come to a better understanding.
If anyone's keeping an account of who's giving out the knowledge and who's receiving then my account's certainly in the red! :wink:

Rgds
Mark

 

[Anonymous]

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[JPEC]

Hi all,

My charnwood fence is still bent, (about 1mm concave), but i do feel better knowing it is not just because i had to go for a 'cheap' p/t that it is so!

Mr Grimsdale
I think it is shocking that a company like Axminster can say that 1mm is within acceptable tolerance, I dont know how many degrees that equates to but it sure isn't square!
How much do you have to pay for accuracy?

Perhaps ally fences should be described by manufacturers as fence 'holders' as it seems that everyone has to fix a piece of timber etc. to them to get decent results!

I was thinking about sending my fence back, but I can see this would probably be a waste of time and postage. I'll just have to turn my 10" planer into a 9" :x

It would seem my sig at the bottom should read ' you pay for what you get even if you can afford it!

Julian

 

[engineer one]

jason, not being silly, but how often do you get to plane 9x9
wood??

seems to me that whilst i agree with everybody that it is unacceptable
not to have square fences, i only actually affects us directly when doing
square edge work, and i question the amount of time that in
today's wood buying market, we are able to buy solid wood that is
10 inches wide on the face and edge.

not to belittle the problem, just to consider the work around.

remember too that there are an awful lot of people making money
out of these machines. the factory in china/taiwan, the export agent,
then "manufacturer" main importer, then the selling outlet.

as we all know as the item gets further along the chain, the profit margins
grow. so it is the things like the fences that are outsourced and
unlikely to be the major priority.

honest i am not making excuses, but we must accept that there will
be compromises necessary, no matter how much we spend.

that's why there are so many outside source fences available for
saws, maybe it is only because so few people use p/t's
that the same are not available for these machines.

not sure whether it is available, but wonder whether it might be better
to buy some aluminium angle with at least one arm longer than your
fence is deep, then fix it upside down on the mainfence. that would
reduce the amount the new fence impinges on the cutting capacity.

but obviously there is a smallish market for an after market fence that
is universal.

paul :wink:

 

[Anonymous]

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[JPEC]

Paul,

My heart bleeds for the poor unfortunate manufacturers of these machines, but Jason is right, it's very british to just say 'oh well that'll have to do then'. This will not help any of us in the long run though.
If the manufacturers put a rubbish fence on their machines and get away with it without complaint, what will be next, plastic!!
If they are encouraged to be nonchalant about accuracy what is to stop them becoming the same about safety!
Standards have a tendancy to slip, if nothing is said.
Thanks Jason I think I will complain about the fence on my machine, after all!

Cheers
Julian

 

[WellsWood]

Hello again everybody,

Well, I had an interesting conversation yesterday with Nick Brown (National Sales Manager/North) for Jet UK. Turns out as well as being a thoroughly nice chap, he's Also known as Jetman when "lurking" (his word, not mine) here on UKW - who'd have guessed. Anyway, following some previous discussions we had, he obtained from the Swiss designer the tolerances they work to regarding the fence on the JPT310: 0.3mm for concavity, and 0.1mm for convex.

Technically then my original fence is within Jet's manufacturing tolerances (just!). So as it turns out the Axminster guy who said I would be unlikely to find a flat one was pretty well bang on the money, and I am pretty much back to square one with regard to getting the functionality I thought I'd paid for without a fair amount of work from me. I am loath to return the machine since it is far and away the most suitable model in every other respect, and there may yet be something on the table from Jet or Axminster that makes the situation better. But I can't say I'm thrilled at the prospect of having to make a whole fence assembly from scratch in order to have acceptable accuracy, as seems to be the most likely scenario.

And here we are right back where we came in; what is acceptable accuracy, and what is is a reasonable expectation from a machine such as this? For me it would be a fence that produces consistent results, once set square to the table, regardless of either the dimensions of the timber or the fence's position across the table, since that is surely it's very purpose. But it would seem that the plethora of manufacturers who fit aluminium fences (and the associated shoddily designed support mechanisms) made to tolerances that essentially make the fence worthless would disagree.

Unsurprisingly, there are a lot of you out there with similar problems, and you have my sympathies believe me. I would urge all of you who think you've been shortchanged to get on the phone to the retailer / manufacturer and SAY SOMETHING. You don't have to scream and shout or jump up and down threatening legal action - don't forget, it costs manhours and therefore money to answer calls and deal with complaints whether the customer is irate or not. If enough people do this sooner or later those cost cutting exercises that leave us with substandard machinery (and deep holes in our bank balances) will cease to be the cheap option!

Mark

 

[JPEC]

PS.

Timber only has to be 10" on the face to stop you being able to plane it, with 9" of available blade.

 

[JPEC]

Well said Mark.

To the phones everyone!

Julian

 

[Anonymous]

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[JPEC]

They seem pretty 'loose' tolerances to me when when some concrete floors have to be within 4mm over 50metres.

Julian

 

[Waka]

Mark

Got home this morning and I've just spent an hour in the WS playing arond with the fence on my JPT 310.

I measued the flatbess all aling the fence and I can't find any distorsion at all, I was unable to get a feeler gauge between the engs sqaure and the fence, when sqauring the fence to the table its spot on.

This does go to prove thatit is possible to get a non distorted fence, maybe I'm just lucky.

Not sure how you can solve your problem unless you unless you put a false front on it. I agree that you shouldn't have to do this but it might be the only answer.

Have you done any test runs yet?

If your interested I can post some pic's tomorrow.