Unreasonable expectations??

[WellsWood]

Have you done any test runs yet?

Hi, Waka.
Yes did quite a careful test yesterday, catch it on page 2 of this thread.

 

[dedee]

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

Which goes back to my original point earlier. If these tolerances were part of the technical spec and available to you before purchase you would either a) Not have bought the product or b) bought the product because of other benefits and accepted a certain amount of tweaking would be necessary and have had no cause for complaint.

Andy

 

[-David-]

I think a little more transparency from 'made to a price' manufactures would be a more honest approach.

The premier manufactures could say in their sales literature and on their packaging -
'Our equipment is made to a tolerance of +/- x%, if, unfortunately your unit is outside these tolerances you may kick us in the shins.

For other manufactures, they could say something like -
'Our equipment is made to a tolerance of +/- y% which is outside what is required for 'fine' work. We have done this to make the unit more affordable by not carrying out expensive time consuming checks and adjustments at our factory. We rely on you, the end user to carry material adjustments and fine tuning. We appreciate that this will take you some considerable time but at the end you will have an accurate and affordable machine.
Below you will find detailed illustrated instructions of how to check and fine tune your machine.'

At least that would put some perspective on purchases.




David

 

[Johnboy]

I have just drawn this out on CAD and the angle error of the jointed edge will be just under 0.3 of a degree at worst case(when the height of the timber coincides with the max concavity) If you a jointing a 20mm thick piece then the error across this edge will be 0.1mm, enough to cause a problem in my view.

I think I would make a hardwood fence to correct this and try to make it easily removable to make it quick to regain the full jointing width.


John

 

[Anonymous]

Mark
Ask a local machine shop to skim it for you. £10 or-so and all should be OK

Alternative is to fit a wood (MDF?) face to the fence with a 0.3mm packer in the middle

There is no need to make a new fence as either of the above will fix it

 

[WellsWood]

I think a little more transparency from 'made to a price' manufactures would be a more honest approach.

The premier manufactures could say in their sales literature and on their packaging -
'Our equipment is made to a tolerance of +/- x%, if, unfortunately your unit is outside these tolerances you may kick us in the shins.

David

Excellent idea David, how about getting them to put M.O.F.A. stickers on the appropriate items while you're at it. :lol:

Johnboy, good point about an easily removable fix, hadn't thought of that. The jointing of boards is not a major issue since it is a standard practice of mine when glueing up a panel is to edge the boards, after thicknessing, from alternating sides so any minor errors are cancelled out.
The real problems start when for example say a table leg has a rail in an M&T joint in each of the 2 adjoining faces, if those faces are not square to each other, and the rails are 800mm long, 0.3 of a degree means (using your figures) that where one rail meets the next leg it will be 8mm out.

Mark

 

[WellsWood]

Mark
Ask a local machine shop to skim it for you. £10 or-so and all should be OK

Is that feasable with extruded ally with 2.8mm thick walls?

 

[Nick.]

Hello Mark, and everyone else, apologies for the delay in replying back on here. I have discussed this with Jet’s chief engineer in Switzerland (He has read this thread through too).

(It makes sense to me, but I know I’m probably about to spark a fresh round of debate )

Rather than try and paraphrase his reply, with his permission, I have copied/pasted his comments below from the e-mail he sent me;

The fence on JPT-310 has double support, and experienced woodworker know how important it is to have a rigid fence that will only flex back a little under load.

The fence is made of aluminum extrusion, and even the best quality extrusion needs a certain tolerance allowance.
We specify between flat and 0,3mm concave, convex not allowed! (a quite tight tolerance for an aluminum extrusion piece this high)
We anodize the fence profile to have low friction and to avoid blackmarking of the workpiece.
This gives the best chance to have many happy customers

He also gave a detailed explanation on the ‘ideal’ set up for the fence;

First of all:
Nobody wants a convex fence with the workpiece rocking on it!

As foud out by practical testing, the best profile shape is slightly concave, with the fence set up slightly below 90° (checked with square on outfeed table next to cutterblock…. Best give about 0,2mm gap on bottom)

Explanation:
-If you are jointing a small workpiece the applied side pressure will be small and not bend back the fence a lot (…low momentum).
-If you are jointing a bigger workpiece the needed side pressure will be higher and further up (high momentum)…leads to more fence bend back deflection

A slightly concave fence profile (ideal about 0,2mm) and setup approx 0,2mm below square compensates for this…you will always get quite square workpieces.

Hope you can follow my explanations.

As one of the comments in the forum pointed out, the result you get on the workpiece is what counts.

I have done a lot of testing on a sample machine, and only can say that good squareness results can be achieved.

Machining the fence for sure is thechnically the best option but costy too (a matter of appreciated value).
-I will have the costs checked (thicker walled extrusion and with machining….will have to be slightly concave too for best result).

Edit - PS, before anyone picks up on the 'quite square' comment - that was his translation, He replied in very good English, but confirmed to me on the phone that he meant 'square'

Best regards,
Nick
Jet Tools and Machinery Ltd.

 

[Johnboy]

I would be wary of machining the ali extrusion to make it flat. This could release stresses from the extrusion process and you may find it would bend along the length.

I don't like the JET engineers explanation much. He seems to be saying that the squareness of the edge will depend on how hard you press the workpiece against the fence. Surely ot would be better to design a fence that did not flex and was flat in the first place.

John

 

[WellsWood]

I don't like the JET engineers explanation much. He seems to be saying that the squareness of the edge will depend on how hard you press the workpiece against the fence. Surely ot would be better to design a fence that did not flex and was flat in the first place.

John

I'd have to agree (sorry Nick, nice try though :wink: ). This is why:

I've just run a little test on mine by putting a square up against the face of the fence and pushing the top edge back REALLY hard to try and simulate what the engineer said. The only thing that I could get to move is the entire fence as the support bracket flexed. The concavity of the fence was completely unaffected (as I was sure it would be). It's academic anyway since to get any movement at all required the kind of force that I would never be able to apply consistently to the workpiece for the duration of the pass, which is what would be needed to avoid a twist in the planed edge. Also, I would hate to think of the possible consequences of my hand slipping while I was pressing that hard ove all those sharp spinny bits - guarded or not. As to the size of the workpiece making any difference this is another non-starter, even if I was edging a 300 x 100 piece of Oak I'm only ever going to apply the sideways force (towards the fence) at a point roughly level with the centre line of the fence - say 75mm from the table - otherwise I run the risk of tipping the timber over the top of the fence.

Having said all this, I do believe I may have a relatively simple fix to the concavity problem that may also work other similar fences, depending on the layout of the webbing in the extrusion, but it's only an idea at the moment. When I've had a chance to try it out I'll write it up here with some piccies (assuming it works of course). [Thinking cap on]

Watch this space.

Mark

 

[Jake]

Maybe you just have to front up the cash for a full-on pro machine (starting at what, twice what you paid?) to get the kind of rigidity and accuracy you are talking about, or buy an old pro machine. I don't think you can get everything for that price.

 

[Anonymous]

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[OLD]

My interpretation of what the engineer said is 'we have a problem getting a flat fence so we only supply concave with a max error' . This is a design and/or quality problem and should be fixed they will then sell more machines.

 

[Jake]

My interpretation of what the engineer said is 'we have a problem getting a flat fence so we only supply concave with a max error' . This is a design and/or quality problem and should be fixed they will then sell more machines.

On the other hand, everything has tolerances, and every tolerance has a price.

 

[Anonymous]

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[andycktm]

Hi, MARK.W
Are you Now happy with the fence?, the outcome of it all?.Are you happy with JETMAN's reply.It's just in your original post you seemed nearly "distressed".Now you seem to have accepted it.I'm about to buy a planer/thicknesser think i'll give the Jet's amiss :roll: .
Over a thousand pound's i would have expected better.

 

[Nick.]

I'm about to buy a planer/thicknesser think i'll give the Jet's amiss :roll: .
Over a thousand pound's i would have expected better.

Andy, of course feel free to look around at alternatives - I know what else is out there in this price bracket, and I genuinely believe the Jet is still the best value/quality for the money you will pay.

It is a very good machine.

I was honest in posting the info. here that came from Switzerland, and I know that it may not have helped our cause depending upon interpretation, but any planer with an ali fence has to be designed within a tolerance at this price. I believe you will find a lot worse designs out there if you look at them in the flesh.

I'd get sacked if I gave exact figures, but we have already sold a lot of these with an exceptionally low rate of problems/issues. I do understand that Mark has an issue, and one of our staff is going to visit him soon in person to check, and see how we can sort it out.

I love the interwebnet thing :-#

Cheers all

Nick

 

[The Restorer]

You'll even find that Felders at £8.5k don't have perfectly flat fences!
:shock: :shock:
An aluminium extrusion will never be perfectly flat by nature of the extrusion process. On higher priced machines they machine the extrusions and, dependant on price, is the level of perfect accuracy achieved.
Your best bet is to probably go with a cast iron machine (not one from the far east or eastern europe) go british, buy a Sedgwick , yes it's more than your Jet , but then your getting more for your money .

It's horses for courses or you get what you pay for. :roll:

If you're in the market for any machine ask the dealer/manufacturer to tell you the tolerances that are vital to you. Then make an informed decision based on what is acceptable to you.

Don't rely too heavily on magazine write ups. Most of them have a lot of advertising from the manufacturers of the machines they are reviewing. Also in this day and age of sue you for anything, do you thing a magazine reviewer is going to stick his neck out and tell you what he really thinks of a machine :wink: He just leaves the really bad bits out!

 

[JPEC]

If we cannot trust magazine articles to be 'honest and truthful' who can we trust, certainly not the manufacturers. No disrespect intended but manufacturers will say whatever they have to , to sell their product.
In the case of cars, Jeremy Clarkson seems to rip various cars to pieces without any fear of retribution!
Surely the manufacturers should fear the impact of a poor review not the other way round!
We rely on magazine reviews to make an informed purchase, if they are influenced by advertising etc. why are we buying their bl**dy magazines in the first place!! :evil:

Julian

 

[andycktm]

Jetman,
Yes i'm sure the jet maybe good value for money,but i find it hard to believe for over a thirteen hundred pounds you have to accept warped/poor fences; from any manufacturer.And whilst ever they are accepted they will keep making 'em.
Your engineer said .3mm was the standard yet .35mm and .4mm was found on his fence!.
Good to see your man is going out tho'.It's not just the machine /tool it's how you are treated after buying it!.