Burns F/A 18X pit

[Mr_Burns]

I have joined hornetpits.org and plan on building my first full simpit.

 

Its going to be a long time in the making I think as I also have to get a house built in the next year or so.

 

Anyway, I got the NATOPS manual and printed the LDG Panel at 400% which seems builders are saying is 'in the ball park'.

 

Its going to be a long drag, I dont move fast! Please can someone help me get started?

 

 

So my first attempt I zoomed the pdf to 400%, focused on the area and hit print. But I seem to be quite a magnitude off a close match:

 

Original?

 

 

Its an inch which is 25mm approx

 

My 400% print:

 

 

Mine is 50mm out. Massive difference, before I have started I have failed!!

 

Is this likely pdf printing to a epsom desktop printer or am I approaching this wrong? I have very limited access to a full size plotter printer but want to make sure I get it right before I ask the draftsmen for favours!

 

Thanks.

Edited December 30, 2016 by Mr_Burns

[metalnwood]

It's too large but seems to be in proportion.

 

If others are printing from the same pdf using the same scale then it is possibly a printer setting you have. the print driver might be scaling to fit page, adding borders, who knows what.

 

Ensure that the scale in the print page is set to 100%. To test, make something in cad of, say 50mm, then print that to check it prints at the correct scale.

 

if it does then you need to change the scale of the pdf with your panel. Measure the size it printed and scale down accordingly.

[Hansolo]

Pardon my ignorance but is it that far off?

 

The picture from The Simulationstore is just shy of 1", appears to be 15/16"about 24mm

 

In your printed version look like about 20mm

 

I would try and print i 402% and see if that got it closer.

 

And good luck with your build Mr_Burns

 

Cheers

Hans

[metalnwood]

Good point, I didnt look at his pics, they look pretty close to me as well.

[Mr_Burns]

Good points, I was thinking when I first looked at the store it seemed much bigger but a few millimetres is fine.

 

Good idea on the test page, I also have a sketch up model I can try and print.

 

Thanks

[Mr_Burns]

Guys I rebuilt my CNC beast, wonder if you can assist.

 

This is a test panel I engraved using Aspire and Mach 3:

 

 

and this was the Aspire page:

 

 

and this was the Dremel bit:

 

Dremel 125 6.4mm Point Tip High Speed Cutter

 

 

I also tried it as 25 degrees.

 

Problem you can see, its just too big a cut for the detail needed.

 

Am going to keep trying but any pointers would help!

 

Thanks.

[Warhog]

The first order of business is to purchase "REAL" engraving cutters. 60 degree, 0.01" tip, .125" dia shank. You will find them wherever engraving products and accessories are sold.

 

Second, choose an Arial font to cut.

 

Third, start by practicing on engraving plastic. Acrylic for engraving will always yield less than great results.

 

If you want to cut acrylic, as a appposed to just trying to engrave it, purchase HSS single or 2 flute .125" dia. end mills. I also cut acrylic with 1/16" dia. end mills. They need to be good quality. Not cheap Chinese end mills or they will melt the acrylic. Buy several as you will most likely break a few as you learn not to take heavy cuts.

 

Those are the most important points other than the accuracy of your machine. I don't expect it will be able to provide the precision required to engrave small sized fonts regardless of your cutters though. A good test is to cut a 1" dia. circle and measure its diameter with calipers in two directions 90 degrees apart and see if they are the same. Then try a 1/2" circle etc.

 

I hope that gets you some better results.

[Mr_Burns]

Thanks John, I only used acrylic as it is all my local homewares store sells, thought I would try that and stock bits but if that is probably the issue I will buy a few decent products to try and make up for a DIY solution with a poor router.

 

If a real ngraver is 0.01 then I think I can see easily why I am immediately off the mark by a long shot!

[Razi]

I get pretty satisfactory results from painted clear acrylic on my scratch built CNC router.

 

I use this engraving tool with a 0.10 tip at a depth of 0.2mm and fill it in with white paint.

 

And I used this font: MilSpec33558

 

I attached a picture of an ELEC PWR panel I had lying around.

Edited January 30, 2017 by Razi
reformatted for clarity

[Mr_Burns]

I get pretty satisfactory results from painted clear acrylic on my scratch built CNC router.

 

I use this engraving tool with a 0.10 tip at a depth of 0.2mm and fill it in with white paint.

 

And I used this font: MilSpec33558

 

I attached a picture of an ELEC PWR panel I had lying around.

 

Its nice, problem I have is the Dremel doesnt have bits like that, Im not hung on the Dremel though, I could easily bolt on a router motor instead, I might look at this.

 

How did you paint the small letters, steady hand and small brush, did you use model paint? Im thinking I will have to do that on the yellow hatched areas of panels.

[Razi]

They offer 1/8" shaft engraving cutters of the same type which should fit in a dremel, see here.

 

After letting the black paint dry for a week, I just blob on a water based paint with a q-tip or small brush and, with a damp cloth, wipe off the excess. I'm not looking to completely fill in the engraving, just want a thin coating of white.

 

Basically, any paint that won't dissolve the base black paint. Then you can easily wipe it off.

Edited January 31, 2017 by Razi
added info

[hansangb]

Razi,

What software do you use with your CNC? To draw, to make toolpaths and to generate gcode?