Member postings for old mart

I have been lubricating the Smart & Brown with 5W30 fully synthetic for years, all the lubrication is oil and total loss, there has been no noticable wear since doing so. Modern oils are light years ahead of the stuff available in the 40's.

It is a waste of a limited rescource to use helium for trivial things like party balloons, there are scientific uses which are much more important. Helium was named because it was detected spectroscopically in the sun before being discovered on earth.

I wish one just like that would follow me home. On the Home Shop Machinist forum, you would qualify for a "you suck" award.

When you have finished the taper turning, pull the cross slide back towards you until it stops (should be back in the same position that it was when uncoupled) screw in the centre plug until it bottoms making sure that the nut is backed off enough not to touch, and then tighten the nut. They do not have to be very tight. The leadscrew should then be back working. I just use a cranked ring spanner on the nut and tighten until you cannot stop the wheel slipping in the fingers.

The choice of holes in the end of the cross slide is the nearest for internal and the rear one for external. The tool height is critical for tapers, it must be exactly on the centre line, or the tapers won't be straight. The whole taper turning attachment is held on the rear of the lathe bed by tee bolts and can be moved left and right to get the taper turning lined up with the workpiece. If you want to copy something critical like a Morse taper. you will need to fix a DTI to the toolpost, preferably the finger type and run it along the centreline of the same size MT set true in the chuck to fine adjust the taper. With that you need to be within a few seconds of arc which is far finer than the scale on the taper turning attachment.

The square heads can be adjusted with pliers or any spanner that fits, even mole grips or an adjustable. They won't have to be tightened much over finger tight, but need the locknuts to keep them from unscrewing by themselves. You will find that TS used Whitworth, BSF and BA fasteners, so get some spanners specifically for work on the machine.

Our mill has the hex headed bolts on the knee, I was muddling them up with the Y axis gib screws.

Some 1/4 drive socket sets have a couple of double square sockets which fit square bolts, you might have some.

I would use the chuck to keep the tap straight for about three turns and then finish by hand. Cast iron is tapped dry, and with a small workpiece you can get some of the dust out by simply inverting the work with the tap still in. Otherwise clean out the hole as soon as you detect tightening of the tap.

Keep any bits of spare cast iron to practice tapping on.

Edited By old mart on 14/08/2022 18:37:43

You first run the cross slide towards you until it stops, and back off 1/8". Holding the wheel, you slacken off the nut in the centre, and then use a hex socket to unscrew the centre part taking the nut with it. The handwheel should be uncoupled from the leadscrew and the cross slide can be pushed away from you.

 By the way, welcome to the forum.

Edited By old mart on 14/08/2022 17:17:43

Unfortunately, to get at the Z raising mechanism in the knee, everything above it has to be removed, and then the knee itself. A taper pin has to be knocked out to dismantle the bevel gears. There is a thrust bearing taking the load at the top of the leadscrew.

The sheer pin dimensions should be in the manual, 1/8" mild steel would do, make a couple while you are about it. The drawings do not show everything there is in the apron, and it takes some doing to understand how things work inside. Both fine feeds are powered by the feed shaft, through the universal joint to the worm and the worm gear. Then the gear change with the arrows horizontal runs through to the rack which moves the saddle, (carriage) or 0, out of gear, to vertical arrows which run through a gear train to the cross slide leadscrew. The worm is held in place by a spring loaded cam which can move to the right if there is resistance to the saddle moving, (hitting the stop in either direction) The movement of the cam to the right disengages the drive. This feature is not intended for use when facing, only axial turning. This automatic disengagement is difficult to achieve, but the fine feeds can be used without relying on it if you are careful.

The gib for the knee is held on by three SHCS which are not noticable at first. They should be only just above finger tight when adjusting the three adjusters with the square ends and lock nuts. You need to carry out the adjustment in the least worn area when the bed is about 5" below the spindle. When the movement seems good, but not binding, then tighten up the three SHCS and recheck. If there is a lot of wear , you might have to run it slightly tight at the ends of travel to give the best results in the middle. Plenty of oil on sliding surfaces and dovetail and on the leadscrew does help. Page 13 in the manual from Denford.

Denford forums have some data sheets and manuals which can be downloaded, the knee mechanism is there.

https://www.denfordata.com/bb/viewforum.php?f=53

Edited By old mart on 14/08/2022 16:34:15

Edited By old mart on 14/08/2022 16:37:27

There are several reasons for the difficulty, wear in the leadscrew nut which allows the knee to drop when lowering, lubrication and the setting of the gib which can vary in tightness due to uneven wear throughout the travel. I have not been able to entirely eliminate the problem even after making a new nut which reduces the backlash to about 0.004".

I bought a long lever to quickly replace the wheel when there is extra weight on the bed which makes raising much easier. The lever might be off a Myford mill, it has 7 indexing lugs rather than a Bridgeport's 8 lugs and is smaller.

You should enter Tom Senior into the keyword box and Manual machines into the topic box. There is a lot of specific TS info there.

Edited By old mart on 14/08/2022 16:16:57

I started this thread specifically to address the problem tramming this particular model of mill which is well liked and nice to use. Over the years, there have been several improvements made by users to the tramming, mostly by controlling the rotation of the horizontal bar that supports the head. I haven't bothered as this was the first time the head had been shifted in two years. One thing I noticed was that if the head is rotated anticlockwise, it will foul the front locking nut unless it is also slid out about an inch when turning it. It could be fixed with a half nut at the front locking position if the rotation feature was used often.

Caps with two locking bolts would have solved this problem at the design stage.

Edited By old mart on 12/08/2022 14:32:57

What would happen if a power diode was in the power supply to the fan?

Some people use a large try square on the bed resting against a ground flat on the left side of the light vertical head. I had never thought of the faceplate method, that could also be used on mills with tilt adjustment also.

I did the tramm with the bed central for zero zero and then at each extreme of travel that the tramm width could accomodate and the ends of the bed were both plus 0.002". The drill mill which cannot be trammed is also 0 - 0 in the middle and 0.002" high at each end. I tried an 18" straight edge on the TS bed and there was no way a 0.001" feeler gauge would pass at any point.

You can grind up a piece of flat steel about 1/3 the diameter of the bore of the coil thick. The steel should be just slightly narrower than the tapped hole and tapered slightly. The end profile should be trapezoidal, so that the acute angle is in the direction of unscrewing the coil.

Edited By old mart on 11/08/2022 17:51:23

I have had trouble getting the light vertical trammed and have just found an easier way to do it. The trouble lies in the clamps which allow rotating the head and also extending the throat depth. The whole lot rotates a little when the clamps are tightened, unfortunately not consistantly. Setting the marks in line gets you within 0.025" over a foot of bed width, and then if the pair of SHCS holding the head onto the shaft are slackened slightly, and the head knocked into tram, tightening them does not move the head to any extent. Tramming that way took 5 minutes, I was lucky that the bolt holes allowed about +- 1/2 degree of movement.

Nearly, but not quite right, the knee being extended by 25mm to increase the Z height slightly has not exactly gone to plan. The knee stops at plus 25mm from the bottom. Investigation found that the top of the nut was running out of leadscrew thread. Not slowly binding, but stopping dead. It is easy to check that it is indeed the nut running out of thread because if the knee is raised to near the top of its travel,and locked, the nut can be screwed up until it stops and the nut height recorded. Then the nut is returned to the bottom of the leadscrew and the distance that the bed can be lowered is the same.

The nut flange has been thinned, and the height of the cast iron base that the nut sits on shortened. The flanges on the nut base are wide enough to foul the narrow underside of the knee, so they have been turned smaller and the bolt seats have been chamfered to use countersunk head 3/8 W bolts (in the post ).

It is possible, just, to remove the nut and nut base without taking everything off of the knee. I rotated the head 90 degrees clockwise and wound the bed right up to it. The nut and base can be blocked up when lifting the last bit and then the knee locked and chocked. The nut on its own can be screwed up the leadscrew and there is room for the nut base to be removed followed by unscrewing the nut. I have added a picture of the modified nut assembly to compare with the old unmodified one earlier in this thread. The screws remain to be sorted at present.

As already mentioned, beech plywood is very good. When I was an instrument mechanic working on aircraft instruments and navigation aids, the boss insisted on getting rolls of the old fashioned lino. It had to be warmed up before unrolling or it would crack. Even in the 70's it was hard to obtain as vinyl flooring had taken over the market. Lino would be ok for clock making and small work, but not for general diy.

99% of my machining is done at the museum, there is no heating in the workshop, but the walls are double with about 100mm of foam insulator, so the temperature only changes slowly, condensation is not a problem. There may be led lighting in the near future which will save on the bills after flourescents.

The museum manager came to me concerned about the ammount of electricity that the lathe and mills used. He got me to switch them on all together while he looked at the power consumption. When he got back and said it was hardly showing, I said, just try that with the office electric heating.