Open sand mould or not

[stevehuckss396]

Looking Good!

 

[Wizard69]

Wow you are well on your way!!! Looks better than expected, you should end up with a very usable table.

 

[stragenmitsuko]

Thx guys .

Had some spare time today , so I continued working on the plate .

This whole router idea started when I got hold of this litle cast frame .
It was part of a larger autosampler machine , and as soon as I held it in my hands I thougt
cnc router .
I've already welded track supports to the sides and machined them .


This frame iis where the t-slot plate is supposed to go .
The base was drilled and tapped , and I pressed in two dowel pins to locate the plate to the base .

The accuracy of the dro will never cease to amaze me .
Two dowel pins , drilled on opposite corners in the base and pressed in .
roughly 500 mm(20") apart .
Drilled thesame two holes in the plate , same drill same press fit .
And they just allign up perfectly .
A gentle tap with the palm of my hand and it almost "clicks" together .

 

[stragenmitsuko]

Then I machined the t-slots .

First the centre section with a 10mm endmill .
Then the actual t slots .

Quite an operation , because I wanted M8 slots , but all I have is an M6 cutter .
So each slot took 3 passes with the little cutter .
One in the centre , and one for each end .

But it all turned out very well .
The cutter didn't brake .

A final pass in the centre with a 45° chamfer finishes the work .

 

[stragenmitsuko]

The t-slot plate on the base , and the pattern, that was made to cast it .

These pictures also show the lineair rails on wich eventually the gantry wil ride .

I must say that I have some porosities in the casting .
Nothing to dramatic , and it'll work for this application , but I guess in the future I'll need to degas more .
I did degas but apparantly not enough .

 

[stragenmitsuko]

Job done , time to clean up the mill .

Why does milling always make such a mess .
Chips flying all over the place , tools everywhere ...

 

[stragenmitsuko]

Another day , another casting .

I wanted to try a split pattern for some time now .
So I made a simple two piece pattern out of mdf .
It's supposed to be a kind of I beam shaped part , but with a flange on 4 sides .
This will be part of the z-axis for the cnc router I'm building

I decided , as I have two flasks to pour it twice , altough I need only one pair of I beams . Just in case something went wrong .
And it did !

The flasks are to small for this pattern to mould it comfortably .
One of the moulds had only 5mm sand between the pattern and the wooden flask . So the liquid metal set the flask on fire , burned a hole in it in no time and all my precious aluminium ended up in the stainless tray .

The other one however had a little more sand between the edges and it went fine .

A couple of pictures .

 

[stragenmitsuko]

This the one that went wrong .

Half an I beam

Lesson learned , at least 10mm of sand between the flask walls and the pattern .

 

[vederstein]

Sir,

I commend you for showing your mistakes as well as your triumphs. In today's world it's too easy to try to present one's world as perfect when we all know life is a pain in the ass with obstacles getting in our way all the time.

...Ved.