what to do with a free scrap dumpster find ?

got the bearing block brackets attached to the base and got the rails mounted on the under side of the saddle so this was just a rough assembly to make sure everything went together. i was going to get a 9" x 31" flat of steel for a table top but think i will make due with the 30" x12" x 1.25 thick plate i have already it's already drilled and tapped as a sub plate with dowel holes the extra width will be handy after thinking about it more the assembly was not bad but would be a lot easier with an extra set of hands it stinks it all has to come back apart to sort the rest out but at least it went together

 

well i thought i had it all figured out but i did not land where i thought i would the original set up was done the same way just less travel since nothing was attached and only held by gravity. since the travel is so short critical speed on the screw is not really an issue if i let it float. the best i could have got was about 14 inches but that did not happen but was able to get 11" vs the original 6" but that's not the end of the world since the clearance between the spindle location and cutting area will be more than this. so it will boil down to finding a sweet spot. one of the pictures shows the end of travel so if you have an imagination you can see what i am talking about

       

Sweet! 11" should do just fine.

spent a week working on my rust bucket truck and had a little bit of time to sort out some CNC stuff for this brain storm this weekend

i was able to get into the spindle to see what was in there from the factory, the bore of the casting is straight through with a sleeve pressed in for the bearings. i think i can press the sleeve out and open up the bore on both ends to to make a new spindle shaft. i had built a BT 30 spindle in the past but i want to keep the casting since its part of the linear way assembly of the original grinder.

the first spindle i made turn out decent it had about .0002 of run out  which i was fine with since i made it a little 10 x 21 lathe. the spindle shaft was not to bad to make since the biggest diameter was 2.750 inches, the only thing i would change would be the bearing OD since the casting is a little bit smaller then what i did for a housing on the first one. the first one had 45 x 85 x 16 mm  bearings but i can get 45 x 75 x16 mm instead for this one. i think i had a bit of overkill on the first one anyways

but the idea is to keep the same design for the shaft and just modify the diameters for the bearings.

some pictures of the prototype spindle i made before. i was also working on some kind of way cover for the back side. i see to much chips falling down and creating problems but that is still a work in progress but i at least have a plan for it now and have stuff gathered up to make something for it

 
 

decided to try a different material this time around, the first one i made from 4140HT but this one i am trying 1144SP because it machines better and is close to the same material. typically something very hard and heat treated would be used but for a home built spindle this a good choice and should do ok, the yield strength is actually a little bit better @ 100,000 psi the 4140HT is around 95,000 psi but it is slightly harder. they are both hard materials but i will soon find out first hand which i like better

steel choices are like Linux CNC to many damn choices

machinedude wrote:

typically something very hard and heat treated would be used 

You could consider having your spindle nitride-hardened. That causes effectively zero dimension change. It is possible to mask it too, so only the required areas are hardened. 

The place that I last used has a £50 minimum charge, though. (  www.longwear-nitriding.co.uk )