Official Luthiers Forum!

Ask Oblio and Arrow.

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Audiences and dispensations on Thursdays ~ by appointment only.


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20", huh ? My deductive faculties lead me to the inevitable conclusion that you have intentions of resuscitating the Stromberg Mammoth ...

And who are Arrow and Oblio btw?

http://celiacasper.com/oblio.html

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

As of today me following in Verhovencs footsteps and refusing to acknowledge
googleable questions.

Quit being so lazy dudes and do your own research from now on.

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Audiences and dispensations on Thursdays ~ by appointment only.


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Actually, I did Google it ...after I posted ... but I still don't get the point ...

Hyuk yuk...

I believe Todd understands me better than a lot of folks who've met me in the flesh.... I don't suffer stupidity very well, and when I ask a question, I want advice, and if you don't have any practical advice to give, don't respond, or in the very least, say what you had to say, then shut up and stay out of it from there forth. But as you said Padloc, I don't have to read your posts, so I have stopped doing so; no clue what you wrote that made Todd respond in kind, but I do know you wasted a lot of your own time writing what it is you wrote. The only time I wasted was scrolling past it, and writing these few lines....

Back to the practical, yes, technique is important, and no, it takes more than 3 minutes. My brother, a cabinet maker, and I can't use the same jointer; what works for him doesn't for me, and vicey versey. The difference is tiny, but it has to do with how firmly we hold the stock against the infeed and outfeed tables. Not noticeable with standard stock(3/4" or thicker), but very noticeable with our thin tonewoods. Sounds like your outfeed table is a hair high; like Todd, I find that I want the knife to carry the straight edge a bit, about 1/8". I fine tune from there, until I get zero snipe if it isn't perfect already.

Back to my question, there's a technique that uses 3 discs or plates, in a similar method to making the straight edges(which I did make years ago, thanks!), involving a master, a A and a B plate/discs. Can someone describe it, or point to a resource? In order to flatten my tables, I want a true, perfect flat surface to register of of.

And back to practical: a machine shop charges roughly $40/hr more than I charge in my shop, so it DOES indeed make sense for me to do my own work. Plus, after learning to do it once, the skill set remains at my disposal for life. There's nothing learned in writing out checks to machine shops.... And finally, once again, it makes good sense to true-up the tables on my 15 year old, seasoned and unlikely to move further, jointer.

When checking the blade height in relation to the outfeed table, you should check both sides of the blade, and check all three blades, as well. If one blade is not set properly, it will cause snipe. Checking with a straight edge on the outfeed table on both sides of a helical cutter head will tell you if there is a twist in the table.

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

Mario: Using the three plate system means you will have to true 3 plates to do one table and 4 if you do both. Lots of work, depending on how bad the tables. Much easier if you could get access to a known surface such as surface plate. That and a bit of mechanics blue will give you an easier route.
Tom

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A person who has never made a mistake has never made anything!!!

Thanks Tom. I have .010" of total twist in the infeed table, and .023" in the outfeed. If I make the 3 plates(I've googled it just now and figured it out) I'll have 3 perfectly flat plates as references when done; why would I need a 4th one?

I do have a surface plate, but it's way too short...

And yes, great advice to check all the knives, and at various points across the entire cutting width.

I think I've got a plan!

I just remembered an old cast iron table that I use to clamp fretboards to necks, and the sharpen planes/chisels/etc.. by fixing abrasive to it. Checked it out, and it, and the tables, are within 1/4" in length of each other. There's my third plate, right?? By lapping all 3, I should have all three perfectly flat when done.

Now, where's that old tube of valve grinding paste.....

Edit: unless there's a problem with my idea?

Grump, I would use machinist bluing and only lap enough to indicate high spots. I would go at those high spots with something aggressive. You could scrape or orbital sand or angle grinder with 80 grit sandpaper disk. Then blue and check again. This is way easier and faster than trying to lap the whole surface with compound or sandpaper stuck to something. When you get closer to flat then you can blue, lap, scrape. You can take it as far as you want. I think you could improve things immensely without too much work. Well other than handling a couple of jointer tables multiple times as you do your flattening thing.
L.

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Cut to size.....Beat to fit.....Paint to match.

Mario: Your right, if your using both tables all you need is the other plate and your in business. I also agree with Link to get the bulk of the material removed. Scraping after that and then your lapping. Some work but no doubt if anyone can do it , you can.
Good luck.
Tom

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A person who has never made a mistake has never made anything!!!

I think the project would be worth a thread here. I'd like to see how it goes. I'm not really understanding what you're proposing so I'd enjoy seeing it come out.

Meddling: One can lap with grinding powder to get one surface to fit another. You can make two surfaces fit together perfectly but you don't know if they are flat. One could be convex, one concave, fit perfectly but both are not flat. The third plate come it and is checked against the two lapped plates. This will show up the lack of flatness in the other two plates. IE the third plate cannot be convex and concave at the same time. Readers Digest version of what Mario will be doing.
Tom

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A person who has never made a mistake has never made anything!!!

I see. So much like the test bars from Todd's jointer set up guide.

Mario, before you start lapping all three plates, I would suggest that you check your third cast iron table for flatness. It may be that the top has been machined flat, in which case you have a head start.

If it is flat, (and sufficiently wide) then what I would do is do is buy three 40 grit sanding belts 6" wide, cut them at the seam and glue them side by side to the plate with an aerosol adhesive. Then have at it with each of the jointer tables. The 40 grit will take them down to flat in no time. Don't even think about 80 grit to start with ...not aggressive enough.

After they are flat, then by all means go to to finer grits , to whatever suits you.

I flatten handplane soles for colleagues regularly in this exact manner, starting off with 40 and ending with 150. I do have the advantage of a 5'x3' surface plate but a smaller one will work as well.

It does rather depend on the third table being flat however ...

Meddling: The same principle, the only way the three plates can match each other is if the three plates are flat.
Tom

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A person who has never made a mistake has never made anything!!!

So, the rep came and had a look. He had a proper length straightedge. Turns out the tables were just fine. His advice was to return the machine because of lack of adjustability. Apparently on helical jointers, you should be able to adjust the height of the out feed table, which is effectively changing the cutter height. He looked at the cut I was getting and said the cutter wasn't biting quite enough. So I've turned in the 6" jointer and upgraded to the 8" jointer which does indeed have an adjustable out feed table.

I'm sure the 6" is great for trueing edges etc. for general cabinetry, but not good enough for what I need it for. I though its size was ideal for guitar making, wide enough for neck blanks etc, long enough for tops, and sure gave a beautiful cut. Small enough to be handled easily by one person. Shame about the out feed table though, otherwise about ideal.

The 8", on the other hand, is one gigantic machine. It wouldn't even fit into my buddies truck. Not sure how we'll get it into the basement....should never need upgrading though. Hopefully I can make this one work. Either that or I'll have to buy (gasp) a plane!

He looked at the cut I was getting and said the cutter wasn't biting quite enough

Yup, that's what Todd and I both thought. Sucks that the outfeed table isn't adjustable, but for a workaround, you could have shimmed the cutter's bearings. Using .001" shim stock, a little trial and error could have zeroed-in to the perfect cut and you'd have been done. I'm sure the 8" will be a great machine, though!

Years ago, Sears sold a 6" jointer with the out feed table that was part of the base casting. The local store was dumping them at a cheap price. I was not too knowledgeable about jointer so I became one of the buyers. Talked to that baby a few times before it was replaced..............!!!!
Tom

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A person who has never made a mistake has never made anything!!!

Ha!

Live and learn I guess. The machine is getting delivered Monday. It seems to have a lot of cool features including some sort of adjustable bits right before and after the cutter heads. I'm sure I'll find more uses for it than just jointing panels. Don't see it as being very portable though. Most of my tools are on wheeled bases to come in and out of the shop as needed....

An appliance cart with a racheting strap from a rent all store and a couple of beefy friends will do the trick. Two guys at the top and one at the bottom, and guess who gets the bottom!

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

If you don't have it in place already, I've moved a lot of stuff in and out of basements using a fridge truck(rental places..) and a buddy. You could, and likely should, open the box, and remove anything substantial but easily removed; when moving items that can weigh many hundreds of pounds, even removing one 5lb item can make the difference between getting it safely down the stars or a trip to the ER....

On my own front, I've found the large plate to be very flat indeed, but a sore shoulder has prevented me, so far, from lapping the tables. That, and I can't find my old grinding compounds... But I have been messing around with a 1x32" 120 grit zirconia belt and a 12" long ceramic stone as a block, and am very impressed at how quickly this removes iron! In just 20 minutes(maybe, maybe even less than that) I have the outfeed table noticeably flatter. I'll try to mess with the infeed table this evening, and might just have a perfectly workable jointer again. If not, it'll be that much closer for when I do get around to lapping them.

Glad to hear it's working for you Mario ... you really don't like spending money do you ... ... but if you insist on using a 1" wide belt ( and zirconia is indeed the business ...I always use Klingspor aluminium oxide ...zirconia is too expensive for me) , then why don't you just glue the belt to a 32" length of 1" wide stock which has already been straightened, and use that as your *plane* rather than the 12" long ceramic stone ? The timber will stay straight long enough for you to get the flatness of the tables in the zone ...