Hi from Australia, Pick a subject for next post

I have enjoyed reading many posts, now I should share some of my good and bad experience. Please pick from the list where to start.

A tool post mounted spindle.

An old mill to a tool grinder.

Repair to a soba rotary table.

4 facet drill grinding jig

gear cutter grinding jig

3 axis DRO to RM45 mill.

Elliot 10M restoration.

I have a small engineering workshop specialising in high vacuum repairs.

Welcome Kevin.

4 Facet drill grinding jig for me.

I look forward to seeing all of them though!

Elliot 10M please

.

+1 on all Vic's comments

MichaelG.

Welcome to the forum Kevin.

Personally I am also always keen to see how folks approach 4-facet grinding.

Neil

Hi Kevin----Elliot 10m for me please

Mick

Toolpost spindle or the mill-tool grinder project please

4 Facet drill grinding jig.

Oops, can I vote more than once?

Hi Kevin D

Greetings from Melbourne OZ

An old mill to a tool grinder. That would be interesting.

Regards
John

Welcome along, mill to grinder for me but all welcome.

Thank you for your reply's. Please be patient the photo's to still be uploaded are post production.

I will combine the old mill conversion with the 4 facet grinding jig. The old mill was picked up at auction some time ago. M3 spindle on large taper roller bearings with a belt drive. The spindle head is on a vertical dovetail slide with a rack and pinion to raise and lower. A fine 3/8"bsf thread for spindle height / depth stop. The height over table was limited, so the pillar holding the knee adjusting nut was shortened. New acme table nuts were cut on the lathe. The old ones had worn to a whitworth profile. New lead screws made and the table re ground. As a mill using M3 collets it was very average. Lots of pounding on the draw bar to release the collets. Have use R8 ever since.

A 50mm dia grinding spindle was made using taper roller bearings. Ref Workshop practice series No27. The original idea was to use a cheap Aldi 5" grinder to power it. After removing the gaiter springs from the oil seal each end it was still puffing and panting. More power was needed. A cheap pistol drill came to service. A flat belt pully was made to screw on instead of the chuck and the drill mounted by the universal round boss behind the chuck. Back to the mill. Remove the spindle and inner perts of the roller bearings. This leave two opposing tapered seats orientated vertical to the table with raise and lower movement and depth stop.

A block of aluminium was bored 50mm for the spindle. At right angle to this a post with a male taper seat to match the bottom taper roller outer shell. A second taper seat was made to seat in top bearing shell. This gave a horizontal spindle which could be rotated about the vertical axis to a limited extent. The spindle is hollow with an ER32 socket and flat belt drive. The grinding wheels are mounted to the spindle in a similar manner to a Quorn, except an ER32 taper size in aluminium with a m10 draw bar is used. This allows the spindle to use wheels or cutters mounted in collets. The wheel is raised and lowered to grind with the x axis used to increase cut. Now this is good for the 4 facet jig. Cut one face and raise the wheel. Rotate 180 deg. and cut the other face without changing the table position. This may upset some readers but, I have a number of wheel mounts with worn angle grinder cutting disks. Cheap and quite ok for gear cutter grinding, the thin 1mm thick disks flex a lot, the 3mm ones are better. As the wheel moves at right angles to it's rotating axis the cut is on the outer edge.

The 4 facet jig is base on Les Riley's design (MEW Feb 2006). The body 110dia by 80 long steel. This was welded to a short piece of 3" channel at an angle of 59deg. Mount in a 4 jaw and machine the angled face, bore 25dia. at an angle of 31deg. Cut off channel and dress outside and cut a 6 x 6 groove around base, dress base and leave a small spigot to locate centre. This allows clamps like those on the rotary tables. Now a few hours on the shaper to cut each side. The ER32 collet chuck with a 25 dia parallel shank has two flats on the body. A perfect location to give 180 deg rotation, an aluminium clamping plate locates on the flats. The clamping plate also has a surface at 22.5deg. on the other side. Reverse the plate to get the rotation for the sixth facet. A M3 holder was machined up with a 25die shank for large drills. This has pin location similar to the original design.

And now a question. At what size do you have to change to 6 facets. I am still having some fun getting parallel primary facets. This must be due to the drill rotated slightly off vertical cutting edges in the jig.

I will try to upload some photos tomorrow, this will give a clearer image to the text. All the parts were modeled on Varicad 3D prior to machining.

I'm more intrigued by what 'high vacuum repairs' are.....

Hi Perko7

High vacuum is mostly used in laboratories. In the range of one millionth of an atmosphere or less. This pressure is low enough to evaporate the oil in a finger print. Common in mass spectrometer and electron microscope's. Primary pumps being rotary vane, diaphragm, scroll, sliding piston etc. Secondary pumps being turbo molecular, diffusion, cryogenic etc. I have manufactured parts and systems for vacuum coating, some automation programming and lots of design work.

Hope this fits in with this thread...

John McNamara says... Greetings from Melbourne OZ

An old mill to a tool grinder. That would be interesting.

I made this tool/cutter grinder using an old flatbed lathe and some other bits I had, the spindle head is from a discarded contact lens making machine and can be moved vertically with the very coarse threaded pillar...similar to the Quorn setup.

The toolpost can be swiveled in x & y axis and rotated about a vertical axis, the whole toolpost assembly is carried on the bed topslide. There is a DTI on the bed to set the amount of grinding so that equal amounts are taken taken off the cutter or drill.

The cutter holder is based on Harold Halls design in his Cutter grinding book and is easily set up for four facet grinding.

Rgds...Bob.

Oh...

should have added .... Welcome to forum Kevin..

rgds..Bob.

Thanks for clarifying the high vacuum repairs, sounds like a pretty specialised field. I imagine the required tolerances would be pretty fine to achieve such a low vacuum with minimal leakage. How does lubrication work in such equipment if the vacuum generated is sufficient to evaporate oil: dry graphite perhaps, or self-lubricating materials?

Hi Bob. I like the way you have found something of limited value and converted it to a valuable and useful workshop tool. A friend used to laugh when I told him I could see an improved watsit hidden in a large lump of scrap. It is an art form that we should all value. Keep up the good work.

Regards Kevin

Hi Perko7. The primary oil sealed rotary vane pump does back stream oil vapour at ultimate vacuum. Hot pump internals cause oil vapour to travel through the vacuum and out the inlet against the pump flow direction. The good vacuum oil is highly refined without colour or smell. No smell equals a very low vapour pressure. The back streaming can be stopped by an activated alumina trap or a cryo trap (liquid nitrogen). Pump clearance is about 5 thou. High vacuum systems usually have a second pump stage of a turbo (electric powered jet turbine), Diffusion ( a stream of silicon vapour drags gas molecules to exhaust) or cryo (freezes and traps gas on panels to lower pressure). Regards Kevin

Thanks Kevin. I've been involved a little in medical and bio-research vacuum systems in a former career, but these did not generate the very high vacuum you are working with. From memory most used either rotary vane pumps or turbine pumps, although there was one system that used water flow through a venturi. I think that one was experimental, as I don't recall it ever being tried again in that application. Maybe it was not able to generate the required vacuum consistently for the tasks it was called upon to do. I do believe that many dentists (in Australia at least) now use suction systems generated by water through a venturi as it can be generated locally, has low noise, uses no oil, and does not involve the high costs associated with traditional vacuum pumps.

It's an interesting field, but one I'm happy to leave the experts to play with. I'd rather reshape bits of metal into something resembling a loco....