The slew base is THE key reason that trading over a month of free time for the ~$1500 you saved over a pre-engineered HF digger, was worth it. It would be silly to back off of that at this point, in my opinion.
Thank you for saying that, I completely agree with the slewing. I know beauty is in the eye of the beholder, but I really like the looks of this thing over the HF.
Having operated both a slewing machine, and a swing boom machine, I believe slewing is far superior.
With any project, there are some bugs to work out; this I normal. I'm not against throwing more money at it.
I see its digging potential, and I'm not ready to give up. The bearing is a problem. a 12" bearing can be had used on ebay right now for $1,000.
I looked into a matching pinion from Kaydon - its $1,200. So I'm going to keep what I have for now. However I sourced a 10" External Tooth Chinese replacement for $160 - but they sure don't give you any load rating, and they can't/wont give me the gear profile to source a pinion.
I added a section of square tubing to the front and back of the legs to support the machine (kinda like your suggestion of rollers) this made all the difference in the word. That base is solid, and I'm not over loading the bearing anymore.
I'm going to adjust it a little bit, and top it off with a section of UHMW plastic to help it slide better.
It can still slew, but depending on the boom/stick angle, only so well. I may need to upgrade the motor.
But anything better says "GPM: 20-30" I asked surplus center about what that means exactly, as they are small little motors, with SAE 6 ports, how could it expect 20GPM of flow?
They never got back to me.
The over-fast cylinders is just too much hydraulic flow. I would suggest using an adjustable flow control valve vs changing the pump, because it removes the possibility of more 'error spending' on pump sizing, plus i think you will find it's just as bad to have the thing be too slow as too fast, so having the adjustability for ~$100 is the 'safe' option in my mind.
I was going to do this, but I 100% don't trust that pump.
Today I purchased 1.93 GPM @ 2000 RPM pump to swap it out. (Surplus Center # 9-7786-B)
As far as some functions seeming fast and some normal, again i think it's just an issue of radius. It looks like all your cylinders are the same size, which means at same engine rpm, each cylinder moves the same speed when you pull the lever. But, when you pull the boom lever you are swinging a 6ft stick, when you pull the dipper lever you are swinging a 3ft stick, and when you pull the bucket lever you are swinging a 1ft stick. The difference in 'tip speeds' might make you think that there is a difference in the controls, but there isn't.
I went and played with it for awhile, and I too think that's what is going on.
Hopefully the smaller pump solves the speed issue.
Below, is plan B if I cant get this thing proper.