Dayton CX150-8 Coaxial Project

[4thtry]

Is that 1/8 MDF or HDF Tempred Board (Hardboard) - smooth on one side and a bit rough on the other

The sign hanging above the pile at the HD big box lumber store said "Tempered" on it. Didn't say if it was MDF or HDF. It is smooth on one side and a bit rough on the other. The sticker on the sheet said 1/8 x 48x96. It is very flexible stuff. The rough side should help the glue to soak in well. I plan on 6 layers, gluing it up 3 layers at a time, for a total thickness of 3/4". Should be a fun process of man against multiple bar clamps!

[4thtry]

Hi,
From my boatbuilding days, I suggest you consider taping your paper pattern to the MDF and piercing it on the lines with a push pin. Then using a fairing batten connect the pin pricks with a pencil line on the MDF. You'll save your pattern and not risk things shifting around when you cut the MDF with your sable saw.

Thanks for the tip. I'll consider trying your recommendation on my next baffle. I have already cut the first baffle using a different technique. Will post a few pictures detailing my process in a few moments. What is a "fairing batten?"

[4thtry]

I'm VERY interested to see how these turn out. Looks like a great design. It might be worth keeping the mid sealed instead of open-back, so you can participate in next year's InDIYana competition.

Thanks. That's the plan.

[4thtry]

A little progress:

My old jigsaw was worn out, so I bought a new one with a high intensity LED to illuminate the work area for increased visibility and a built-in dust blower to direct debris away from the cut line. I also bought a new set of blades. This really helped to improve my cut.

First, I carefully aligned the template to the baffle board along one edge with blue masking tape.

[4thtry]

Then I applied several lengths of double stick carpet tape to the baffle surface. I made sure that the cut line had double stick carpet tape along its entire length. After I rolled the template out flat onto the carpet tape, I made several passes with a wooden roller to provide good adhesion between the carpet tape, the template and the particle board baffle surface. I didn't want the template to come loose in the middle of the cut.

[TN Allen]

Looking at your project, you might want research "hull lofting" and "picking up lines". You may see some new ideas for further projects. Lofting is usually done full size, it's mechanical drafting to produce the temporary molds, or forms, that a boat hull is built over. Sometimes the actual frames are built to the lofted lines, set up, and planked. Boat building, in my opinion, is one of the most complex processes mankind developped. CAD and digital milling have eclipsed traditional boat design and building. Look at a traditional ship and marvel that men thought it through, built and sailed it.

A fairing batten is a piece of wood that can be bent around temporarily placed nails, into a fair or uniform curve, in order to draw a line delineating part of a boat.

[4thtry]

The result was a very clean and accurate curved cut, staying within 1/32" of my template line. With a little sanding, this first piece will make a nice particle board template to create several identical baffles and backs using my router and a flush trim bit. One down, 3 to go.

[4thtry]

I removed the paper template and carpet tape from the particle board immediately after the cut. As you can see, it stuck to the paper and pulled off cleanly from the particle board. I was a little concerned that the carpet tape would stick too tightly to the particle board when I pulled it up. But this didn't happen.

[4thtry]

Looking at your project, you might want research "hull lofting" and "picking up lines". You may see some new ideas for further projects. Lofting is usually done full size, it's mechanical drafting to produce the temporary molds, or forms, that a boat hull is built over. Sometimes the actual frames are built to the lofted lines, set up, and planked. Boat building, in my opinion, is one of the most complex processes mankind developped. CAD and digital milling have eclipsed traditional boat design and building. Look at a traditional ship and marvel that men thought it through, built and sailed it.

A fairing batten is a piece of wood that can be bent around temporarily placed nails, into a fair or uniform curve, in order to draw a line delineating part of a boat.

Thanks. Interesting stuff.

[scottvalentin]

Awesome!! Thanks for the great photos of the process. Good luck with the next steps.

[tomzarbo]

Bill, that looks like the exact jig saw I purchased a year or so ago. With the new T blades it really cuts good I think. Fast too.
Quite an improvement over my last 20 year plus old Craftsman.

TomZ

[Wolf]

Okay- is it a Ridgid jigsaw? The base matches my barrel-grip Ridgid jigsaw, and I love it!

Later,
Wolf

[mattk]

Okay- is it a Ridgid jigsaw? The base matches my barrel-grip Ridgid jigsaw, and I love it!

Later,
Wolf

Looks like a Ryobi to me

[4thtry]

New Jigsaw: Ryobi JS651L1
Blade: Bosch T308BO (T type)

Very smooth cut on 3/4" particle board. Nice LED high intensity lamp to follow my line. As you can see in the pic above, the built in dust blower blew all the dust to the right side of my cutting line. Very nice unit compared to my old one.

[4thtry]

A little progress:

The next step was to sand the curved edge of the first baffle board perfectly smooth and true to 90 degrees. As suggested by emilime75 above, I wanted to use this first baffle as a template to cut the remaining 5 boards. There will be a total of two backs and four fronts, creating a double thick 1-1/2" baffle.

So, just to perform this one brief sanding operation, I spent an entire day making 3 custom sanding blocks; two curved ones and one straight one. This may seem like overkill, but I thought that if I attempted to sand this edge free hand or by using conventional sanding blocks, I could easily make the edge worse by rounding the edges off or over-sanding the low spots.

To make the curved blocks, I started by bolting an extension onto my router's circle cutting guide. Then I cut two large radius arcs from 1-1/8" thick particle board material (see attached pic). One radius was 35" and the other was 15". These two arcs matched the radii of the two curves used to make the initial paper template. I then glued 1-1/8" strips of 100 grit sandpaper along the curved edges.

Then, by gluing flat blocks onto these curved pieces, I fashioned them into custom sanding blocks (see attached pic). These blocks always remained at 90 degrees perpendicular to the baffle at I slowly applied downward and inward pressure to sand the curves smooth.

To prevent sawdust from building up on the inside edge and messing up the sanding operation, I offset slightly and then glued some curved 3/16" hardwood pieces to the inside of the sanding block. This provided a relief channel for sawdust to exit as I sanded the edge. (see attached pic).

This all worked quite well. Using the custom blocks, it took me about 15 minutes to lightly sand all of the curved edges and straight line areas smooth at a perfect 90 degree angle.