Creating an Accurate Template for Veneer Panels

[SvenG]

I think I may have figured out how a shipwright accrurately cut veneer so it fit within an existing frame, but I'd like to toss it out here to see if I'm right and if there are any additional tricks I need to know.

The trick is how to accurately measure or alternatively trace an outline of the enclosed surface so that it can be transferred to the veneer for accurate cutting.

I think what the shipwright must have done is to use thin battens/strips that he temporarily glued to the inside edges on the enclosing frame. He probably used hot-glue or booger-glue to temporarily affix the strips so as to form an accurate outline of the enclosed surface. If there was any curvature he would have had to sand or otherwise make the strips conform to the edges. Then I assume he used permanent glue to bridge the joints between the strips so that they would stay in place relative to each other. Once that was all done I'm assuming he pulled the template away from the surface, removing any remnant booger-glue or hot glue.

The resulting template could then be used the transfer the interior outline to the veneer for accurate cutting.

Any shipwrights here who can tell me if that is how it is done ? Any hints on what to use for the strips/battens for the best rigidity ? How about what glues to use for the temporary bonds ? Any other hints ?

Thanks in advance,


-Sven

PS I based my guess on having found a glue gun and short broken pieces of thin plastic around the area where a shipwright was doing the interior veneer work for a new porthole.

[Patrick_DeepPlaya]

You could also use cardbaord, we did. I learned that trick from a guy who installed our countertops in my house.

[capt_douglas]

I'm not a shipwright, but I'm familiar with the use of 3" wide flexible wooden strips and a hot-melt gun to get make an accurate template of a complex or difficult location. The carpenters cut the final product a bit bigger (maybe 1/16") because it's easier to sand than glue.

[SvenG]

Originally Posted by Patrick_Seattle

You could also use cardbaord, we did. I learned that trick from a guy who installed our countertops in my house.

Do you mean to use cardboard strips or use one piece of cardboard for the whole template ? That was probably for surfaces where you could use a trimmer to cut off the excess rather than trying to fit perfectly inside some frame ? Thanks.

Originally Posted by capt_douglas

I'm not a shipwright, but I'm familiar with the use of 3" wide flexible wooden strips and a hot-melt gun to get make an accurate template of a complex or difficult location. The carpenters cut the final product a bit bigger (maybe 1/16") because it's easier to sand than glue.

Great ! Thanks for confirming the general process, now I know I wasn't imagining how it could be done. Off to find a source for the wood strips and a glue gun.


-Sven

[Patrick_DeepPlaya]

Full sheets of cardboard... cut with a box knife or pieces stacked and glued to create the right angle or edges if necessary. The hard part I've found is not soo much the shape, but the bow or flex of the panels. There will be much fine tuning. I loved my Fein multimaster to shaving down the high spots.

[SabreKai]

I use strips of old paneling ripped on the table saw and then cut to length as needed. each one is cut to fit, and then all are glued together and pull out when dry.

Sabre

[Ex-Calif]

The way I have seen it done is as follows.

Insert a template made from thin ply at the narrowest point which is smaller than the original panel.
Measure the widest width to create a datum
Using a rod and pencil trace the outside of the shape onto the template
Make a mirror template, top and bottom template as required
Cut the template outlines
Clamp the templates on the final piece and transfer the shape
Cut the final piece

The attached cartoon tries to demonstrate.
The left side is the left template in place being traced
The right side is mirrored templates (dotted lines) on the final piece

[delmarrey]

You can use a joggle stick or what's called tick-sticking. The joggle stick spreads out like a fan from a larger panel and the points contact the farthest points and then one draws a line between the points creating curves or angles.

But I prefer following the interior, where one builds a trellis of sorts with 2-4" long sticks, following the shape of the hull then adding longer sticks to fill in the middle. Ice cream sticks work great. You can break them to the right length.

I have stringers in my hull so one can not just draw a line between points.


.

[capt_douglas]

Good comments all.

My biggest concern with the cardboard is that it's not dimensionally stable, tends to curl at the edges, and is a bit soft when it comes to edge hardness.

[forsailbyowner]

I use 4 mil builders plastic for my patterning needs. Along with a roll of mylar double backed tape and a fine point sharpie. Makes the whole process very easy. Also easy to do complicated forms that may not be practical using battens.

[Surveyor]

Would careful measurement not suffice? Using one side as a baseline, measure the other 3 sides and the 2 diagonals?

For irregular sides, offset from the corners a known distance, take the above described measurements but this time to the intersections of the offset lines and also station out the offset lines at intervals and then measure over from those stations to the irregularities.

Kinda like....surveying

[sarafina]

Originally Posted by Surveyor

Would careful measurement not suffice? Using one side as a baseline, measure the other 3 sides and the 2 diagonals?

nope. boats are not square and have a dimensional factor for the curve of the hulls. Measuring is not going to get it.

The batten plan is a good one. Stone installers, working with pieces of unforgiving marble and granite use this system. By outlining the site with battens that are hot glued in place you get a pattern that exactly fits the space and accounts for any 3rd dimension.

If you think teak and mahogany are expensive... try pricing high end stone for countertops!

[bob kingsland]

I use 1/8" door skins or any 1/8" ply for patterns... ripped into strips about 2" and cut to fit. Glue with hot glue gun by putting smaller pieces on top of the joins, not overlapping 1 piece to the other. Overlapping usually causes problems when transferring to the finished part. This is a pattern for 1 of my main sole pieces:
and this is a stack of patterns and sole pieces in the shop:
For veneering the dry fit has to be about perfect, and the pieces will expand when it gets wet with whatever you use for glue, testing your patience. The pictures are not veneer; the teak and holly is actually 1/4" thick, but the pattern making is the same.

Best, Bob S/V Restless

[SvenG]

I really appreciate all the answers, ideas and inputs.

Soon I'll get to try to put all that new info to good use !



-Sven

[waikikin]

Hi, the process of templating that a shipwright generally uses is known as spiling- for taking off the shape of planking or bulkheads etc. A very rough template is costructed using battens/craftwood/ply/hotglue/screws/tacks/whatever is available, a spiling block(in the case of planking) or a spiletto for more irregular shapes or for reference of fastening holes beneath applied contruction is used- the method is as used in tick stripping or joggle sticking as more modernally described. The spiletto is applied to the template & carefully traced around- often referencing a line or point of the desired shape & personal notes/measurement/hiroglyphics made to the rough template. the template once complete with markings is transfered to the planking stock or bulkhead material etc & the spiletto replaced to the template & markings and the points & lines of the desired shape marked up to the material & you typically "join the dots" , cut out the material & with skill , experience & practice acheive a nice fit up of the component. I often use a 1' or 300mm steel rule as a spiletto as conveniently available or cut a bit of ply or 3mm craft wood to a strait edge on one side with a V cutout, a semi circular cutout & a square cutout withe the opposite side describing a gentle curve to a point- the "blunt" end being about 1 1/4" & square off the strait side. The cut outs allow referenceing of the spiletto accuratly back to the rough template- measurements by rule are not nessasary & an old joke amongst Shipwrights is that "the tape measure or rule is overated" especially considering the very common 100mmm errror. Hope you understand as its late here & if I work out how to post a picture one day it would tell a 1000 words or even more!. All the best in your endeavours from Jeff.