Questions, primarily to owners of Proxxon DH 40

PoulD

PoulD

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Location
Roskilde Denmark
In order to try and build the Blandford X-section I have tried to make a thickness planer from an ordinary hand planner. Unfortunately I'm not satisfied with the performance. When I try to make some plates and meassure different places the thickness may vary up to apr. 0,1 mm along the plate. Worst in the first few cm of both ends where I can even feel kinda waves. I don't think it can be improved to my satisfaction so I'm now considering alternatives:
1) I can give up scratch building, at least for the time being.
2) I can try making a thickness sander instead, but I have no idea if the outcome will be better than with the planner.
3) Already from the beginning I firmly decided that I would not spend the amount of money a DH 40 cost (also as I don't know with certainty if this is the one and only time it would ever be used). But now I have started asking myself again if the DH 40 could be considered. It does not make sense. Am I retarded? The definition of insanity is doing the same thing over and over again and expecting a different result. I have very clearly and unequivocally said NO!!! so why do I keep asking myself the same question again?

Unfortunately I used to be a Salesman so I'm not that easy to get rid of so I answer myself: 'Could be you had changed your mind? Or maybe I can persuade you with some good arguments to change your mind?' Thus I wonder if I can find some really good arguments to persuade myself. Using Google I can't find any information about the precision nor about the accuracy.

Questions to owners of DH40: Say you plane a couple of plates, e.g. 50 x 300 mm to a thicness of 6.35 mm and you measure the thickness with a micrometer screw gauge at different places, what is the max. variation you would find?
Questions to all: If being a real stickler, how much variation in thickness on frames /spants would be acceptable at scale 1:48?

PS: Byrnes thickness sander is out of the question (transport cost would be huge and Denmark has some of the highest taxes in the world so with VAT + import tax + fee for handling import declaration to customs etc. the price would end up at the wrong side of a month salary
 
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OK WITH MY 2 AND 1/2 CENTS, I HAVE WHAT IS CALLED THE LUTHERIES BEST FRIEND USED BY INSTRUMENT MAKERS, GUITARS, VIOLINS ETC GOT IT FROM AMAZON I THINK SOL D BY STU MACK, COST $220.00 HAD IT FOR ABOUT 3 YEARS NOW IT ATTACHES TO MY BENCH DRILL PRESS NOW HAVE 3 MACHINES IN ONE DRILL PRESS, THICKNESS SANDER AND SPINDEL SANDER, I HIGHLY RECOMEND THIS I WILL POST A PICTURE OF MY SET UP IF YOU ARE INTERESTED, HAVE USED THE SAME DRUM FOR OVER A YEAR CALLED A ROBO SANDER 3 COME WITH IT, JUST FINISHED DOING SOME MAHOGONY FROM 1/16TH TO JUST UNDER 3/64 FOR CUTTING FOR PLANKING STRIPS WORKED OUT GREAT HOPE THIS HELPS GOD BLESS STAY SAFE YOU AND YOURS DON
 
dear Paul
I understand your deliberation and the questions.
I can tell you that the Proxxon DH 40, it's simply excellent and gives full value for the price.
I purchased very recently (see the blog on the subject).
Your situation is relatively better because within the Europe, shipping costs are lower than for shipments over longer distances outside Europe or the United States.
In conclusion, I highly recommend saving for the moment when you identify an attractive sale, try axminster 20200808_231332.jpg
 
@donfarr: Thank you very much. I found some picturess on the internet of 'Luthier's Friend Sanding Station'. It gives me new hope: If I build a thicness sander myself I'm confident I should be able to achieve at least the same precision as with this one. If that is good enough for the purpose then I don't have to spend a fortune on a 'DH 40' for now.

@shota70: Thank you to you too. I have with interest followed your blog about the 'DH 40'. Your blog is also partly why the DH 40 is still on my mind. However, the price with Axminster in the UK is 4,650 DKK (735 $) which is about the same as the price in Denmark. I don't know if it is expensive or cheap but either way, it is a whole lot of money and way beyond what I had in mind to spend on the project.

I would still very much like to hear in numbers what kind of precision one can expect from the tool and also what kind of precision is to be dessired for parts such as frames in a 1:48 scale model (should it be 1/48 of the precision I would aim for in full size? in that case maybe < 0,02 mm?)

Thank you in advance
 
Watch out for any device that uses a drill press as a sanding machine. It is inherently risky. Drill press chucks are held in the quill by a friction-fit Morse taper. They are designed for vertical stress (up and down drilling). If lateral pressure is placed on the chuck, the taper can come loose and the chuck fall out of the quill while the chuck is spinning. Such a flying chuck can be a very dangerous thing. At least the bottom of the sanding drum should be inside of a hole in the base to minimize danger to yourself from a chuck that drops out. This setup would probably get you a failing grade in shop class.

John
 
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bartley said:
Watch out for any device that uses a drill press s a sanding machine. It is inherently risky. Drill press chucks are held in the quill by a friction-fit Morse taper. They are designed for vertical stress (up and down drilling). If lateral pressure is placed on the chuck, the taper can come loose and the chuck fall out of the quill while the chuck is spinning. Such a flying chuck can be a very dangerous thing. At least the bottom of the sanding drum should be inside of a hole in the base to minimize danger to yourself from a chuck that drops out. This setup would probably get you a failing grade in shop class.

Jhn
Click to expand...
Thanks for the heads up. If I build a sander it will most likely be horizontal. In any case it will be with fixed roller bearings each side of the sanding drum.
 
PoulD said:
in that case maybe < 0,02 mm?)
Click to expand...
Just my opinion here Poul. I have have a Byrnes thickness sander, a full sized thickness sander, and a planer. Going down to <0.02mm is a MUCH greater level of precision than needed for model building work. For automotive metal machining yes.. for wooden models no. I do my CAD drawings down to .002mm of accuracy but for the actual fabrication of parts on my CNC machine, I am ok with a billet that is flat within 0.3mm of accuracy. Anything less than that and we are just talking a couple swipes of a sanding stick.
 
mrshanks said:
Just my opinion here Poul. I have have a Byrnes thickness sander, a full sized thickness sander, and a planer. Going down to <0.02mm is a MUCH greater level of precision than needed for model building work. For automotive metal machining yes.. for wooden models no. I do my CAD drawings down to .002mm of accuracy but for the actual fabrication of parts on my CNC machine, I am ok with a billet that is flat within 0.3mm of accuracy. Anything less than that and we are just talking a couple swipes of a sanding stick.
Click to expand...
Thanks a lot Mike. Quite a relief. I'll try to build a DIY sander for now (at a later stage I might buy a DH 40 if I seriously get caught in scratch building).

May you have a good day
 
PoulD said:
Thanks a lot Mike. Quite a relief. I'll try to build a DIY sander for now (at a later stage I might buy a DH 40 if I seriously get caught in scratch building).

May you have a good day
Click to expand...

Here's what I'm doing.

Another homemade Thickness Sander

To continue from another thread, I was asked to post info and pics of my thickness sander. I have all the other stuff from full size to mini size to break down and make model "lumber". I have made California Redwood and Michigan Poplar sticks down to 3/32" square and can do them down to 1/8"...
shipsofscale.com

EJ
 
HI ALL THE LUTHERS BEST FRIEND THAT I USE, WHAT THEY CALL THE ROBO SANDER , MADE JUST FOR THIS PRODEUST WORKS LIKE YOU SAID THE SET UP HAS A HOLE AND THE SANDER RECEES ABOUT A LITTLE OVER A 1/16TH HAVE BEEN USING IT CONSTANTLY FOR OVER 2 YEARS NO PROBLEMS, REMEBER THIS TOOL EAS DESIGNED FOR INSTRUMENT MAKERS GUITARS, VIOLIONS ETC. GOOD ENOUGH FOR THEM GOOD ENOUGH FOR ME, AND THANKS FOR THE SAFETY TIP I WILL BE CHECKING IT EACH TIME I USE IT. GOD BLESS STAY SAFE DON
 
From my point of view. 1/10 mm is for me a good result. This is as well the maximum deviation with my DH40. Its wood, not metal.
Finaly i dont build a Saturn V, only a wooden ship from the 17. century :) and i cant see any problems with this tolerances.
The waves are "normal" with this kind of technique. After the planing i cut both ends. This little pieces i use for smaller parts or for testcuts or whatever.
Nothing is for the trash in my shipyard.
 
Hi Poul,
I would be interested in seeing some photos of your router jig.

Olivers Historic Shipyard said:
From my point of view. 1/10 mm is for me a good result. This is as well the maximum deviation with my DH40. Its wood, not metal.
Finaly i dont build a Saturn V, only a wooden ship from the 17. century :) and i cant see any problems with this tolerances.
The waves are "normal" with this kind of technique. After the planing i cut both ends. This little pieces i use for smaller parts or for testcuts or whatever.
Nothing is for the trash in my shipyard.
Click to expand...

My limited experience with thickeners is similar to what Oliver has said, I would add that the thinner the material the more problems.

Also at 1/48th or 1/4" to the Foot scale .5 mm=1" or 25.4 mm so .1 mm = 5 mm on the real thing.

Cheers,
Stephen.
 
@Stevedownunder: Hi Stephen
Stevedownunder said:
Hi Poul,
I would be interested in seeing some photos of your router jig.
Click to expand...
Some pictures in this post #621

Stevedownunder said:
Also at 1/48th or 1/4" to the Foot scale .5 mm=1" or 25.4 mm so .1 mm = 5 mm on the real thing.
Click to expand...

yep, match what I calculated, hence I was worried (If I go to the local wood shop and buy a board for my house I would never accept 5 mm variation in thickness). Making a double frame in worst case the variation could accumulate.

@Olivers Historic Shipyard: Thank you very much Oliver. Maybe, from a pure precision perspective, my planner is not so bad after all then :)
From another perspective I still don't find it very good. The wood is squeezed between the sole of the planner and the 'under-table' in a far too big area. This is causing a huge friction so I need to push with a lot of force to get a board through. This friction is also causing less precision due to some elasticity here and there and it is pain in the b... coz it means I have to pass a board many many times. To overcome this I think both the fore and aft sole of the planner would have to be removed and replaced by rollers (preferably even motorized rollers). I don't think that is possible, at least not with the rollers near the cutter.
I'll give it a try making a DIY thickness sander and cross my fingers . . .
 
I built my own thickness sander and I am totally satisfied with its performance. I sized the drum for boards up to about 7 or 8 inches wide and a max of a little over 1" thick. There is no end to the debates about bigger is better; each person has to decide their own requirements.
The height adjusting screw is a 1/4" dia. bolt with a gear attached at the bottom. One rotation of the bolt raises the planer surface 0,05" and since the drum is halfway between the bolt and the pivot-hinge, the distance between the drum and the table changes 0.025" per revolution of the bolt. Yesterday I sanded a piece of walnut to 0.020" thick with no trouble. Any thinner and I wouldn't be able to push the piece through without buckling. There are ways to use a thin sled (1/4 inch maybe) to attach ultra-thin stock to for sanding, but I haven't done it.
I made the drum using a number of discs (~3" dia.) using a hole-saw in my drill press to cut the discs from 3/4" plywood and glued the disks together onto the 1/2 dia. shaft. One of the discs near the center was reinforced with a metal pin (piece of a nail) through the shaft and nested into a groove on the side of the disc., then more discs glued on to complete the drum. Attached are a few photos of my planer.
Happy Modelling
Steven
 

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