Friday, February 24, 2012

37.5 percent loss

Continued making cabriole legs. It is always a good thing to make a few extras!

First side of blanks milled.

Here is the first 12.5%. I placed the blank wrong way in the holder. It's the left one.

Then I changed some parameters in the milling software and forgot to make a holding tab. A holdingtab is a part that is left behind in the milling-process and then keeps the part in place.

37.5%. One of the legs just disappeared on the workbench. Of the eight leegs I started out with there is just five left.

When glueing small parts a caliper is very handi as a parallel clamp.

Hand milling groove for backplate.

Sides of lower part of highboy isready to be attached to the front frame.

Lower part ready for mounting of inside drawer dividers

Have fun

PS: Someone may have noticed the change of coin from euro to american quarterdollar, that's because I'm working on a seminar presentation for The IGMA Guild School in june. Title will be something with CNC and miniatures.

Friday, February 17, 2012

Frontframes for Highboy

Test fit of lower drawers.

Horizontal drawer dividers.

Vertical drawer dividers. I choose to make a frontframe instead of attaching the horizontal drawer dividers into the side panels.

I made some extras. You will notice that some of the dividers is a litthe thicker that's because the upper drawers is a little too small.

Test fit of large drawers. Looks good to me.

Free verticals. Ready to mount.

 Just put on some glue in the grooves and then mount the verticals. I'll wait to mount the small top verticals until the glue has set.

And because the horizontal dividers is still in the frame everything is perfectly square. When the glue has set the front frame is sawn free and ready for next step.

Have fun

Wednesday, February 15, 2012

Modern jig for cabriole legs

The modern way of making jigs is named CNC.

The lower part of the "Bonnet-Top High Chest" stands on four cabriole legs. The thinnest part of the legs is about 0.5mm so a little testing has to be done. 

This is the screen from the computer that controls my small cnc-miller. 

The drawing of the leg is first scanned into a CAD program and the contour is traced. Then the CAD-drawing is transformed into codes understood by the CNC-miller by another program.

Here the first side is milled out. The large parts at the ends is later used for holding the leg sqare when cutting the other side.

To ensure excact reference this pocket is milled in a piece of MDF.

After the first cut the leg is rotated 90 degrees and placed into the pocket.

And secured with holddown clamps. (the mdf is mounted on the millingtable with double faced carpet tape.)

Then second side is milled out.

And the leg is ready for next step.

CNC is fun and a great help but you still have to understand how a piece of furniture is made.

Have fun

Wednesday, February 8, 2012

Start all over ?

Do you know the dilemma?

You are halfway through making parts for a project and you find a better way of making the parts.

What to do?

Continue making parts the "old" way and remember until next time same projecttype shows up on the workbench or scrap what have been made until now and then remake the parts the "new" way.

Have fun

Wednesday, February 1, 2012

Fun in the kitchen

 While waiting for milling cutters I took up an old skill. It is about 5 years since I made the last photoetched part for miniatures.

I found some good photos of realsisize Queen Anne style brass pulls and escutcheons to be used on the "Bonnet-Top High Chest"

Real size is 3 1/8 inch across that gives 1.65mm in scale 1/48. A few details have to be left out :-) 
A little work with a drawing program the photos is transformed into a black-and-white photomask.

Below is the testprint of a lot of the brasses and the resulting photo-mask scaled down to 1/48 scale.

Then to the kitchen because running water is a must.

First cleaning a piece of 0.1mm brass sheet.

 Then adding a photosensitive film to both sides of the brass sheet.

There are two ways of using this film; either dry or wet. The dry process requires a laminating machine with great pressure from the rollers. I don't have one.

The wet process can easily be used in the amateurs workshop and there is very little difference in the next steps. The photosensitiive film is protected by a thin plastic on both sides.  One of the plastic layers is removed and the brassplate is submerged in cold water and the unprotected film is then placed on the brass plate. The assembly is then taken out of the water and the water and airbubbles is squeezed out so te film adherers to the brass. After short drying eventually with the help of a hairdrier the plate is ready for exposure.

Exposure requires ultraviolet (UV) light en mass. My UV source has four UV tubes and is controlled by an old dark-room timer. 

After a few tests for checking sensitivity of the film and blackness of the photo-mask I got this. Exposuretime 30 seconds.  The film turns light blue when exposed to UV. Developing the film is done in a light solution of soda ash. (10grams to 1liter of water)

 Ready for the etch.

Etching is done in a strong solution of ferri chloride. A nasty stuff. Leaves brown marks everywhere if not removed immediately but it is one of the best solutions for etching copper and brass.

In my etching tank there is an aquarium heater to raise the temperature to about 30deg.celcius and an aquarium pump supplies some air bubbles to circulate the solution. That makes the etchiong process go faster. I forgot a photo of the etching tank and now the kitchen is cleaned up :-)

Result of todays work.
Better than expected.
I stopped etching with a little bit of brass left (to the left :-)

And a little closer.

The brass is still hidden under the photo-film. I'll strip off the film and polish the brass when I am ready to mount them.  Stripping the film can be done with either a strong solution of soda ash (1cup to 1liter of water) or with acetone.

Todays etch was a little experiment too because I etched from one side only. That way I didn't have to make two films and have them lined up before exposure. Also I didn't need tabs for holding the parts from falling off and then dissappearing in the etching solution.

Have fun