RobCox
Member
- Messages
- 541
- Location
- Cambridge, UK
I've decided, wisely or otherwise, to try and make a power feed for my Eagle surface grinder. Yes, a J&S 540 would be very nice but it would be too expensive - lack of space means I'd need a bigger workshop. I've come up with a design that will hang off the boss behind the table X feed handwheel, but at the moment this is just a rough casting and it needs to be machined smooth and true to the axis of the handwheel shaft. The size of the SG cross slide means it'll have to be done on the mill although I'm running out of work envelope pretty fast. I intent to use the horizontal spindle so the cross slide can lay flat on the table. I was going to hold my boring head in an ER collet chuck but there's no room:
So the first thing I've had to do is to make an int30 to 1 1/2 - 18tpi UNEF adaptor. This gave me a chance to use the taper turning attachment on the lathe for the first time and it made life really easy. The taper was easy enough to set up with the DRO (3.5" / ft taper) and the fit came out ok for a first try:
After that I used the Ainjest to cut the 18tpi thread up to the shoulder. Being a tightwad the threading insert is a re-profiled DCGT insert in a homemade holder:
After milling the slots for the drive dogs I tried the boring head in the horizontal spindle:
It won't get much lower profile than that. Space is still tight but there's just enough room to fit a short boring bar in, however, as I'm going to be boring on the outside of a feature I'll have to run the spindle in reverse which inevitably will lead to the spindle adaptor unscrewing, so I drilled and tapped the boring head for a grubscrew and fitter a copper slug over the thread to stop it getting mangled:
So I arrived at this setup - just mocked up, the cross slide isn't clamped down yet:
The next problem was pretty quick to spot. It's a 2" boring head and I need to turn the casting boss down to about 2.75". @Smouser very kindle offered to loan me a brand new 3" boring head he has but I'd have needed to fit a grubscrew to stop that one unscrewing, and as it's not mine that wasn't a path I was going to go down. So, enhancement part 2. After a few hours in the workshop I've made an extension for the 2" head:
Time will tell if it'll work or not, but its got one job to do and will probably never be needed again.
So the first thing I've had to do is to make an int30 to 1 1/2 - 18tpi UNEF adaptor. This gave me a chance to use the taper turning attachment on the lathe for the first time and it made life really easy. The taper was easy enough to set up with the DRO (3.5" / ft taper) and the fit came out ok for a first try:
After that I used the Ainjest to cut the 18tpi thread up to the shoulder. Being a tightwad the threading insert is a re-profiled DCGT insert in a homemade holder:
After milling the slots for the drive dogs I tried the boring head in the horizontal spindle:
It won't get much lower profile than that. Space is still tight but there's just enough room to fit a short boring bar in, however, as I'm going to be boring on the outside of a feature I'll have to run the spindle in reverse which inevitably will lead to the spindle adaptor unscrewing, so I drilled and tapped the boring head for a grubscrew and fitter a copper slug over the thread to stop it getting mangled:
So I arrived at this setup - just mocked up, the cross slide isn't clamped down yet:
The next problem was pretty quick to spot. It's a 2" boring head and I need to turn the casting boss down to about 2.75". @Smouser very kindle offered to loan me a brand new 3" boring head he has but I'd have needed to fit a grubscrew to stop that one unscrewing, and as it's not mine that wasn't a path I was going to go down. So, enhancement part 2. After a few hours in the workshop I've made an extension for the 2" head:
Time will tell if it'll work or not, but its got one job to do and will probably never be needed again.
