Thread: Hembrug lathe on the way.

Originally Posted by Greg Q

Thanks Mark...

Don't know about knowledgeable, but I certainly have missed the comradery here. Now that I am a month away from getting the roof on I am letting my thoughts drift back to exactly why the garage floor is 8" thick in "the shop" annex.

Wow has it been so long that you can't remember the rules of engagement around here! Sigh, you should now the deal ... pictures or it didn't happen Let's see the Moose Mansion!!!

Patience, grasshopper. I will get some better shots once the roof goes on. The entire house is made of vibration-damping concrete, 740,000 kg so far. Should make for a stable machine base assuming my remaining lifespan is longer that the endless list of things to do on the building.

GQ

Originally Posted by Greg Q

The entire house is made of vibration-damping concrete, 740,000 kg so far.

GQ

Oh, you did the environmentally friendly version?

Oddly, it was billed that way. Halfway through the ours I discovered the carbon footprint of cement, did the math and discovered the energy savings pays back the CO2 in 88 years. Never if you factor in cheap solar. The majority of the concrete is structural though...there's hardly any cement roman statues.

I think concrete is second only to plutonium in terms of environmental impact! Which is why I love it so much. Concrete that is, plutonium? Not so much.

there's hardly any cement roman statues.

Well, that's your housewarming present sorted then!

Originally Posted by Greg Q

Thanks Mark...

Don't know about knowledgeable, but I certainly have missed the comradery here. Now that I am a month away from getting the roof on I am letting my thoughts drift back to exactly why the garage floor is 8" thick in "the shop" annex.

Suppose u will be sending the Hembrug up this way for grinding now. Although in your extended absence you might have missed that bit of news. Along with the three tonnes of granite that turned up.

I thought that was a fever dream...RC and a slideway grinder...the mind boggles at the possibilities...

The only problem with that is the stupid headstock and ways are one piece. I think the Dutch rig up some kind of bar through the spindle bearings which acts as the support for a cup grinder which does the ways.

Which, by the way, are hardened. Really hard too, like Rockwell C 62 or something silly

GQ

Originally Posted by Greg Q

I thought that was a fever dream...RC and a slideway grinder...the mind boggles at the possibilities...

The only problem with that is the stupid headstock and ways are one piece. I think the Dutch rig up some kind of bar through the spindle bearings which acts as the support for a cup grinder which does the ways.

Which, by the way, are hardened. Really hard too, like Rockwell C 62 or something silly

GQ

That is all right.

I have a cyl grinder as well. To grind up a test bar to align the bed for grinding. I will only charge the equivalent to five nights accommodation, which you graciously paid for up front back in 2011.

While the Hembrug ways might be hard. I bet my CBN wheels are even harder.

I am speechless.

Well while you are speechless you have some catch up reading to do. Got carried away a bit on this project -->> Jafo Jarocin mill repair.

Okay, made some progress the other night, the power feeds were not working at all, so I have had much more of a dig into the saddle mechanism and I have found some issues, looks like its been dismantled but not reassembled properly, thankfully I have the manual diagrams, I need to remake part numbers 13, 14, 21, 20, 22 in the below diagram, part 21 carries the key that takes drive from the leadscrew and 14 seems to be the interlock that prevents the half nuts and power feed being simultaneously engaged.

I dont think any of those parts are beyond my means but I do not understand why 21 doesn't just take the drive directly from the pins in 19, why does part 20 exist, I dont think anything moves backwards or forwards so it isnt a dog clutch, some kind of shear protection?
hembrug_DR-1_00-25.jpg

I dont have any metric broaches at all (this is 6 or 8 mm i think) I am thinking about turning down the ends of say 3 m10 grub screws and use those to take the drive, maybe turn them off centre and then rotate them to get a just right sliding fit, any other ideas?

Regards - Ralph

Part 20 looks more like a coupling so any misalignment does not get passed through the system.

Michael

Hole in one Michael, great observation. How close a fit would you imagine it to be on the leadscrew, im thinking fairly close maybe 0.004" overall, or should I leave enough for swarf to pass through?

Hi Ralph,

I agree with Michael, it looks like an anti miss alignment coupling. I assume that it is missing, since you include it in the list of parts you need to make. It does make me wonder if it could have been made from a hard rubber or some other semi flexible material. Its failure could be why the saddle has been dismantled at some time and not been reassembled properly with all its bits.

I think shear protection is limited to the stripping of the drive gears. Seeing how many AI-DR-1's I see with brazing done to the apron I'm guessing that the in-built protections are not robust enough to prevent expensive crunching sounds from the feed mechanism. Oddly, I never see those repairs on the pictures of the European machines. Is there a difference in operating philosophy?

I met a guy in Los Angeles some years ago who had both a Hamburg DR-1 and thirty years experience as an aerospace machinist. He cautioned me to ensure that my feed clutch was adjusted to disengage at the first contact with the (adjustable) end stop at the headstock end of the lathe. He's the guy who sold me the sets of replacement feed gears.

GQ