Thread: The Journey for a Master Square

I was thinking about spindle run out(or can the laser do that also?)

The pdf if great! going a little OT here
Does the CNC use scales, resolvers or just count steps?

Stuart

No scale or resolvers, just counting steps.

The process for painting the pattern was:
- first sand the pattern to 240grit.
- I use sandpaper glued to what ever form I need. i.e. a larger flat surface for the sides, dowel close to the radius of the inside. I make up the flat blocks from a scrap of pine with a sole of cork (from floor tiles). You can level it up quickly using some sandpaper on a flat surface. The cork has a little bit of give in it. Scotchbrite style sanding pads work well for blending in curves.
- I then used some thinned down shellac with some talcum powder in it to raise the grain and make sanding easier.
- Sand it back again
- Then I primed it. (btw: Don't use el cheapo fiddly bits "grey primer" from a large retailer. It seems to be more of a description of the colour than its use.)
- Then I used a coat of spay sealer putty.
- Any small dents etc. were filled with spot putty.
- It was then sanded back using wet and dry.
- The above three steps repeated until all grain, dents are filled, shapes flow properly.
- Followed by a final undercoat and a rub down with some fine scotchbrite abrasive pad.

Now that's pretty much the ideal process. The problem was the el cheapo primer I used. The stuff just liquified when using the primer putty and spot putty leading to all sorts of problems. So there were more cylces to rectify crazing and pitting when sanding.

Christian

Some more pics...
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So is most of the error as simple as the step being off a little in the software so an easy fix?

Thanks for the painting details.

I was wondering why you've place the pins so symmetrically? or are they that good that there isnt a "wrong way"?

Stuart

I hope its a SW fix. I've contacted Tormach to see what can be changed. Tormach have a locked version of MACH3 on the controller so I don't want to go fiddling too much.

With regards to the pins next time they won't be so symmetrical (or i'll add a third pin). One way it fits perfectly the other means its out by ~1mm. Not so obvious. I'll also mill them at the start so I can reference the two halves more easily.

Next time I make up a pattern there's a few things i'll do differently. At least from the list Josh and Ray have I think there will be plenty of chance to sort out the procedure ).

Christian

Just about to install/epoxy some re-enforcement sleeves for the pins.
Roughed up to provide the epoxy a bit of mechanical grip
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Sleeves installed and tapered pins machined to match.

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Next job is to decide what colour to paint metrology patterns. I'm thinking prussian blue..

Hi Josh,
A little late now but are taper pins of that angle such a good idea?
I would assume if the tapers lock onto the pins at all they will have problems separating the mould.
Of course if the sleeves arent tapered none of that applies.

Fingers crossed for a SW fix Christian.


Stuart

Originally Posted by Stustoys

Hi Josh,
A little late now but are taper pins of that angle such a good idea?
I would assume if the tapers lock onto the pins at all they will have problems separating the mould.
Of course if the sleeves arent tapered none of that applies.

Fingers crossed for a SW fix Christian.


Stuart

Sleeves are not tapered...., it "grabs" a little too much at the moment on just the last 4mm or so of the straight section of the pin at the end of the taper. The pins are not fixed in yet. I think I will bore the pin out a little and screw them into the sleeves so they can be removed from the cope half of the pattern at some stage down the track.

I'm off to find some paint...

-J

A trip to the store and a coat of "prussian blue" latter

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das ist wirklich schön )

Christian

I see you went for canode blue not Marco blue

Really nice job guys