How I mark my cuts.

[CAOS]

Hey everyone,

I thought I would share my version of laying out cut lines. I got the idea of sharing this from a previous thread on the Garage Journal. It may seem like overkill but in my experience it works when I do not use the plasma table and I want multiple accurate pieces.

I first start off with a with a line drawing of what I want to make, then scan it and print off the number of pieces that will need to be cut. I then cut the shapes out.

Next step is orientating the shapes on the piece of material from which the pieces will be cut from. In this case it is some 1/4" and 1/2" plate.

I then use some spray adhesive to attach the template to the material.

I then use a light color of spray paint and dust over the templates(I used pink in this case, just because it tends to get a rise out of the GJ). The reason I do this is when using the band saw to cut the shapes out, the coolant makes the paper all soggy and it ends up falling off. You are then left with a perfect outline of the shape. The paint gives you a great "scribe" line to follow while using a grinder to touch up the piece.

Its a very simple method that proves to have great end results. This method also helps to make all of your center punch marks very accurately and consistent when doing multiple pieces.

 

[Jack Olsen]

It's a smart way to do it.

I do something similar for curved pieces I'm going to cut. Print it out, stick it down, then spray paint around it.

 

[T1320T]

Good technique... simple, accurate & effective.

 

[Jack Olsen]

Sorry to clutter the thread, but here's a case in point: when I wanted to make a wing for my race car, I printed out the airfoil I wanted, cut it out with scissors, and then lightly adhered it to some plywood. The pieces I cut out of the plywood became the jig that I used to make all of the shaped aluminum supports inside the wing. I was able to reproduce the complicated shape over and over again with very little variance -- without ever measuring, drawing or marking anything.

The shape:

Transferred to the wood:

The cut-out buck:

The supports:

The pieces:

The wing taking shape:

 

[e-tek]

Thanks for the lessons boys.

Hey Jack - how did you finish it? I'm waiting to see if you bent the sheet over the supports, or ?

Is there a lot more of us from SK here lately??

 

[CAOS]

Is there a lot more of us from SK here lately??

The city that rhymes with fun!

 

[FarmWrench]

Nice wing. If that is a cunk likely to end up junk; could you line the first larger wood patern with sharpened steel and make a cookie cutter to stamp blanks with a shop press? Then use a second die to form the edge without all the trimming? Or was this a one time, never to be crashed project?

Durring the war they made P40's in Buffalo NY and used a radial arm router to make parts off wood patterns. Just a big router bit with a bearing to ride the pattern cut 4inches of stacked up Al sheets at a wack.

How did you get the scan/print thing to work to your size as I never get the right size? TIA

 

[MP&C]

Here's another method for marking cuts using CAD (concrete aided design) and laser guided sharpies...... It's what I used in my EWheel fabrication


Once laid out and marked, the cut off wheel did a nice job on the 20 degree cuts for the back legs....

The leftover pipe from the rotisserie build came in handy....

Back on its feet:

 

[NASTYZEN]

Hey Robert, nice legs.
Gives it that able to run away look to it.You should paint it zebra scheme.

 

[CAOS]

I use the floor at work all of the time for larger layouts. I always get funny looks though. Never thought to use the laser line though, awesome!

 

[A_Pmech]

That's a great idea!

I usually use paper patterns and stick them to the steel with Scotch 77. I don't use coolant, opting for a blade oiler instead. Much less messy and it doesn't screw up the paper template. You can also spray fast drying laquer over the paper template, this works best with laser printed stuff, but will work with many inkjet inks too. The laquer dries in 5-10 mins.

 

[Yojinbo]

My mind is growing (again) guys, thank you all for sharing.

 

[Jack Olsen]

Thanks for the lessons boys.

Hey Jack - how did you finish it? I'm waiting to see if you bent the sheet over the supports, or ?

Yes, I wrapped it around. Not particularly well, but it works.

Nice wing. If that is a cunk likely to end up junk; could you line the first larger wood patern with sharpened steel and make a cookie cutter to stamp blanks with a shop press? Then use a second die to form the edge without all the trimming? Or was this a one time, never to be crashed project?

How did you get the scan/print thing to work to your size as I never get the right size? TIA

The wing's lasted for about four years, so far. The part that finally started to fatigue was the round tubing that connected the two halves.

To get the right size, I printed it out with trial and error, basically. I adjusted the enlargement percentage until it matched my chord size.

 

[cnc-me]

That's a great idea!

I usually use paper patterns and stick them to the steel with Scotch 77. I don't use coolant, opting for a blade oiler instead. Much less messy and it doesn't screw up the paper template. You can also spray fast drying laquer over the paper template, this works best with laser printed stuff, but will work with many inkjet inks too. The laquer dries in 5-10 mins.

I know you won't be using this method for any real exact,but I have
found the Laser printers to be not as accurate as the Ink Jets.
I guess its something to do with transferring the toner to a drum.

 

[MBfreak]

Hi.
Regarding printer accuracy
1
Never use a drawing form with a border. The X/Ydimensons are changed slightly by the program, at least in Autocad. Just use the "no template" sheet with no borders
2
Laser printers tend to change dimensions slightly on transparent media. I make my own PCBs for electronic hobby projects. Printing the exact same drawing on paper and PCB template media on a laser printer gets different dimensions between the two, after they have cooled down. Inkjet does not.
3
PCB templates with 2,54 mm module spacing with ie 40 DIL sockets is quite demanding when it comes to accuracy. A 1% error ( 1% of 2,54 mm *20) will make the template useless.

My $ 0,02´s worth on using printers for templates.

Ola