Drummond Round Bed Lathe No 1

[rtbcomp]

I've just acquired two of these, this is about getting the first one, nearest the camera, up and running.



The first thing I noticed was that when you screwed a chuck on it jammed the spindle. This was because the spindle was too far to the left due to some washers which were placed between the bearing and the locating collar. These were removed and the end-float taken up by moving the pulley to the left. There is now some clearance between the chuck thread and the bearing.



Sorting this also allowed the change wheels to line up properly.



There was no means of locking the final change wheel to the leadscrew, so a spare spacer was drilled and tapped 1/4 BSW and a grub screw made to secure it; so now the spindle turns freely and drives the saddle.

 

[rtbcomp]

Next job was to get the treadle mechanism working. The con-rod that came with it didn't fit the crankpin, so it was obviously the wrong con-rod.

I made a new con-rod by doing a cut and shut on a pair of Metro (K-Series) rods, the gudgeon pin slipped nicely over the pin on the pedal and the other little end was drilled out to fit the pin on the flywheel/pulley.



The assembly twisted slightly during welding, but that can be sorted when a friend with oxy-acetylene needs to return a favour.

The clanking is the whole thing rocking on an uneven floor, it's actually quite quiet in operation.

 

[rtbcomp]

The next problem was when I tried to line the treadle up with the lathe, although the (homemade) base that came with it fitted the stand I made for my other Drummond,


there was not enough clearance for the belt, so I'm in the middle of modifying the stand to suit.

 

[slim_boy_fat]

The clanking is the whole thing rocking on an uneven floor, it's actually quite quiet in operation.

@rtbcomp That looks too much like hard work - you planning a motor?

 

[rtbcomp]

^^ I haven't tried it under load, but it's surprisingly easy to work, even to stop and reverse.

I have plans in the back of my head for motorisation, but one step at a time.

 

[cumbriasteve]

Nice mod with the con rod and always nice to rescue old stuff if space allows

 

[rtbcomp]

@MattF came up with the correct con-rod, so after a swap the treadle is now original

 

[rtbcomp]

Another little tweak. The intermediate change wheels were retained by a standard nut rather than the proper one which meant they either came loose or locked up depending which direction they were turning, so the nut and shaft were drilled to take a split pin.

 

[rtbcomp]

Just weighed the treadle unit - 40 Kg.

Bits came for the support frame for the treadle today. Once it's in place I'll know what to get in the way of a belt. It needs to be a flat belt, 1 inch wide. Lathes.co.uk are asking about £26 for a belt and a joiner, which seems a bit expensive.

Edit - Flywheel/pulley alone weighs 27Kg

 

[Bill Edwards]

Just weighed the treadle unit - 40 Kg.

Bits came for the support frame for the treadle today. Once it's in place I'll know what to get in the way of a belt. It needs to be a flat belt, 1 inch wide. Lathes.co.uk are asking about £26 for a belt and a joiner, which seems a bit expensive.

It's called balata belting, as I recall. Google may reveal some cheaper suppliers now you know the name of it. I can't remember who I used to supply mine as it's a long time ago now. I have a roundbed too

 

[rtbcomp]

Thanks @Bill Edwards, found a few more places, prices seem much of a muchness.

 

[rtbcomp]

Spent a whole day faffing around mounting the treadle, making brackets such that the thing can be moved in 3 axes to line up with the pulley on the lathe, make sure the belt doesn't rub on the stand and the lathe is horizontal and the flywheel/pulley on the treadle is vertical, and that my knee doesn't crash into the stand on the upstroke.



Belt and clip should be here next week.

 

[rtbcomp]

Belt came today, bought it from these guys https://www.ebay.co.uk/str/EUREKA-STORES (looks like they're on holiday at the moment).



Runs very smoothly and quietly. I may need to incorporate a tensioner, but we'll see when I try it under load.

 

[MattF]

How true was that piece running, according to the DTI?

 

[rtbcomp]

About 5 thou out of true along its length, which means it was a concentricity issue. I had already shaved a bit off the backplate but didn't touch the register. This cured a progressive error as you moved the DTI further from the spindle. It's a (Metro) gudgeon pin which I'll keep as setting up tool.

I've had a go at facing off both ends of a bolt, one end was the threaded end and the other where I cut the head off. I'm making a new tool post stud.

I had the belt come off when I got a bit heavy with the cut, set to fasted speed. I changed to the middle pulleys and it worked better. This balata belting is a bit awkward, you pull the ends tight to get the joint, but it's like a wet flannel when in place.

 

[rtbcomp]

Finished the tool post stud, this is the old one, you can see the damaged thread and the need for spacers because it was too long.



I used a decapitated M12 bolt for the stud and a ground-down cage nut to fit the T-Slot on the compound slide



The finish is a bit rough and ready, but it's my first encounter with a lathe.



I also replaced the tool clamping screws with new cap head machine screws. One of the originals didn't even reach the tool shank.

I've just got to file the M12 nut down a bit so a 3/8 BSW spanner fits, this will reduce the number of spanners I have on the bench at any one time.

 

[Pete.]

I've just got to file the M12 nut down a bit so a 3/8 BSW spanner fits, this will reduce the number of spanners I have on the bench at any one time.

If you get hold of a flanged M12 nut the spanner will fit perfectly.

 

[rtbcomp]

^^ Interesting. I used what I have in stock, literally 1000s of metric fasteners left over from a business I used to run.

 

[Pete.]

M12 flanger are 18mm hex which is almost exactly 3/8BSW hex size. In fact I don't have that BSW spanner so I use a 18mm for Whitworth

 

[rtbcomp]

I fitted an idler wheel (Metro K-Series timing belt tensioner) to work on the back of the belt. It takes up some of the slack and puts more belt in contact with the pulleys.

I also made a collar to act as a spacer when using compound gears.




Facing off, truing up the bar, drilling the centre all went well until it came to using the 10mm drill bit. The belt just kept slipping and it was really hard work operating the treadle, so the workpiece was moved to the pillar drill, complete with chuck and the hole drilled out to 1/2 inch. It was then put back in the lathe and bored out to the required 5/8 inch diameter. That was a bit of a job, the 1/2" hole wasn't sufficient to let the boring bar in far enough, so I had to part off and bore from both ends.

Parting off was a nightmare. No matter how I adjusted the saddle the workpiece climbed up onto the tool and jammed. This was traced to worn chuck jaws. I eventually parted off with a hacksaw and faced off on the lathe.

Bear in mind all this was done using the treadle, the worst part of which is trying walk afterwards. The left foot keeps lifting 8 inches into the air while the right foot lifts the usual 3 or so. Plans are afoot to fit an electric motor.

I've changed the chuck after facing off its backplate and using the parting tool, although hard work, isn't impossible any more.

Next project will be a base to screw the chuck to so I can attach it to the pillar drill table.