Reconditioning a Relmac lathe

[irving2008]

Keith/Robin

Thanks for your comments.

I am not entirely sure I understand your point Keith, I don't think its an airlock issue as there was plenty of room for the air to come out, I am pretty sure its a heating issue, thats the furthest corner from the fill.

You will note in the previous attempt (which didnt have the shim all the way into the spindle) that that side filled OK but the other side failed. I am wondering if the best option is to have two fill points, one through the top and one to the side to fill from the bottom up initially and then from the top.

Keith, your casting experience is far greater than mine and this is clearly a 'casting' problem so I am grateful for your thoughts. I am a little loath to heat the metal a lot more as I have read that overheating causes some of the trace elements such as antimony and bismuth to leach out, but I don't know how hot that means - I cant get anywhere near hot enough to boil it!

I will persevere... it will come right one day...

[irving2008]

Irving, My thoughts are that the shim (shown in red) needs the ends trimming to the yellow line to allow a fast and full fill, I think with that modification you will have success.

One uninterrupted pour till metal flows out of the vents (funnels?) maybe use a plumbers mat under the work area to catch the excess metal.

You'll know when you have overheated the metal...Fumes and smoke will start to emanate :)

Keep safe and enjoy the experience matey

I think you may be right, but if that was the case why did it work OK at the other end? Maybe something to do with heat distribution... and when I did have the gap in the shim it failed to fill OK on the other side????

Obviously I'm not chanting the right incantations when i do the pour. The main issue with cutting the shim is that it makes the shaft very hard to remove if its solid metal round it. What I might do is taper the shim back towards the outside so that there is a full gap by the shaft and I can get a junior hacksaw blade in the slot to remove the metal where the shim tapers to fully slot the bearing to remove the shaft

I did have one uninterrupted pour... it flowed out four of the 5 vents but not the last one as the pictures show!

Funnily enough I was thinking on the lines of a wooden dam and it would be easier to make into the right shape - what I actually need are two 50mm x 3mm discs with a ~37mm dia x .5mm deep recess and a 32mm central hole with some cutouts for vents... maybe I should make some up...