DIY Epoxy composite gantry frame milling machine

**pippin88** · 09-12-2018

John,

Can you give us an update on the results of the first pour?

In particular - how is the alignment / flatness of the bearing mounting plates?

I've been doing a lot of reading, and am pretty sold on epoxy granite due to the excellent damping characteristics.

If I can cast in a linear bearing mounts with acceptable accuracy at home, and avoiding the need for post-machining, I'll be out the door for 20-40kg of epoxy.

Also, can you share how much the Megapo

**John McNamara** · 10-12-2018

Hi Pippin

I will be posting the results soon, my workload has piled up so have not had much time for the machine.

I have managed to prepare and undercoat the casting, there were more blemishes than I would have liked, I filled them with body filler and the part is now undercoated. The part is very massive too heavy for me to lift. Tapping it with a hemmer yields a dull click only, even on the metal parts. the damping propertied of mineral cast epoxy is clearly evident

A prelim check with a straight edge indicates that the cast in position rail mounts are accurately located and co-planar . By eye I was unable to see a gap. However I will feel happier when I have tested them properly. Now that the part is clean I will set it up on jacks on surface plate to take some proper measurements.

Regards
John

**John McNamara** · 12-12-2018

Hi All

I have reviewed the accuracy of the casting and am very pleased. Link below.

https://www.model-engineer.co.uk/for...?th=139042&p=2

The maximum error is 0.0018" as cast, that will be reduced by lapping to high accuracy there is not a lot of metal to remove so the process will not take a lot of time.

Regards
John