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Tool post grinder build Clough42 inspired
PekkaNF:
And funny how it is nearly impposile to punch ug out with hole saw when there are releve holes for swarf o disappear...I did not have rotabroach that big and deep, therefore joys of step drilling.
Bar stock is 60 mm OD mystery aluminium, bit gummy and not nest to cut. But I have one metre of of it.
So, I turned OD to fit to split clamp.
Then I set over one jaw of the three jaw chuck one tooth. Oldest trick in the world.
And proceed to stepdrill to 22 mm in three phases.
And then joys of enlarging the hole to near 38 mm with boring bar....carbide inser pruduced pretty rough bore, no matter what I did. I gave up and digged HSS insert and put grove to it. Still needed an cutting oil to produce good enough finnish. This material would be galling against similar AL like there is no tommor. Luckily I have steel on both sides.
Pekka
PekkaNF:
Next challege was a motor plate:
1: I used belt calculator to see what is correct shaft distance and used it as mid point. Then a little experimentation that proved it righ. The big idea was use nominal shaft distance as a mid range - loosen to minimum and belt should come on and off. In the end reality seemed to confirm theorio exactly.
I draw features on the plate just to make sure I don't do something stubid and miss the target metric inch or something...
Tightened the mount plate on the milling vise over paralles, centered on spindle clamp and moved table calculated distance.
2: Motor mount using DRO PCD-function.
Motor mount has a flange OD near 25 mm OD and 38 mm PCD four M4 mount. First time ever I use DRO PCD function. needed a little study and two YT tutorials.
Second thing where to put the holes. Eccentric gives some latitude, but because it provides also belt tightening a little drawing etc, calculation, guestimation and stuck-and-see was order of the day.
M-Dro mill DRO worked exactly like the manual said. Some features were not very intuitive or logical....like "0" to CW PCD calculation or giving start and end angles for first and last hole, but thinkking it over carefully before making the holes worked fine.
Nice feature is that hole locations can be accessed multiple times with up/down arrows. I could check approximately I would be drilling on exact locations, could drill them 4,5 mm clearance holes (for M4 screws) and then use 8 mm slot drill to make pockets for bolt heads.
Then I mounted 25 mm rotabroach, moved back to zero point (centre of the PCD) and made last hole.
After deburring and wash was exiting moment to tryrif all mounts correctly. They did.
Next step is figure belt guard, grove to use hex keys for motor pulley set screws (a little tight fit between pulle and mount plate) and see in which direction to mount motor cable exit.
I haven't fiqured out exactl how to mount the grinder/drill. I was thinkking of using the same dove tail patern as QC-toolpost, but now I see trouble with that and probably will go for more traditional Dunmore post type......or something like that.
RussellT:
That's looking good. Does the clamp work OK for all positions of the eccentric? I was wondering what happened if the slot on the eccentric was on the far side from the clamp slot.
Russell
Sea.dog:
Nice work, Pekka, but you seem to a problem with the PCD function. The rear two holes definitely look off centre from the scribed circle.
PekkaNF:
--- Quote from: RussellT on October 20, 2019, 03:58:59 AM ---That's looking good. Does the clamp work OK for all positions of the eccentric? I was wondering what happened if the slot on the eccentric was on the far side from the clamp slot.
Russell
--- End quote ---
The eccentric is aluminium and the collar has some spring back. The M5 screw needs a fair nip but not near nominal torque to tighen all in a pacage. The clamp screw clearance hole needs a litte opening and closing slit as well. Weld pulled it a little out of round and when trued in lathe it needs a little more tightening than 0,9 mm slit allows.
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