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Start of Tom Senior refurbishment.

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Simon Williams 309/08/2019 14:27:57
399 forum posts
65 photos

Many thanks for the fascinating pictures of the needle roller bearing supporting the driven pulley, that looks as if Mr Senior (Senior Junior?) had second thoughts about the bronze plain bearing that I found in mine and went for the needle rollers, presumably for later models.

The other interesting difference is the splined quill shaft - mine is a single long keyway driven by a captive key. I fancy the spline is a much better job, but I guess needs an investment in the appropriate tooling to make it.

Do you have a serial number? Yours must be a later machine than mine.

I've just measured the bore through the quill, I make it 10.9 mm so 7/16 ain't going to go.

Keep us posted, do!

Rgds Simon

old mart09/08/2019 16:46:14
444 forum posts
42 photos

I don't have the serial number at present, but it seemed to be of 1969 vintage. All the major cast iron parts have the build number 7, except the head casting has no number I can find. The bed is the long style. I was going to make the top half of the spindle, with a mill and rotary table, it is easy to cut that style of spline. Now I am going to cut the bottom off the existing spindle and attach it to the R8 end. The drawbar will be made of 7/16" 431 stainless steel, the only stuff I could get in 400mm lengths. The bottom 3/4" will have the 7/16" UNF thread, the remainder will be turned down to 10mm and the top will have a 10x1mm thread for a 19mm af long nut with locknuts either side and a bronze thrust washer. If there is room inside the spindle above the R8 tooling, I might be able to make it self extracting. I was worried about fitting the two halves of the spindle together. There will be 1 1/2" of close fitting overlap, plus 1/2" of 26tpi thread pulling the halves up to a shoulder. I looked in the Loctite site for a sleeve and bearing fit retainer that did not go off too fast. I have 638, but fitting the parts together and screwing them up tight might have ended badly. 620 is a much slower curing grade and should be fine.

ps, the s/n is 2961

Edited By old mart on 09/08/2019 16:51:59

old mart10/08/2019 20:08:20
444 forum posts
42 photos

Today, I finished the outrigger lower bearing holder and the spindle. The two halves of the spindle fit with about 0.0006" clearance and screw together. I forgot which thread pitch I had used in the bore of the lower section, and to make matters worse, I have lost my unified thread gauge. I searched the cupboard of unknown measuring equipment and found a little thread gauge with 26 and 28 tpi. It turned out to be 28 tpi. Now I have the two halves screwing together with the minimum of clearance, I now have to wait for the Loctite 620 to arrive.

Mike made a special spanner to hold the spindle when the drawbar is tightened and released as there is no large pulley to hold in the TS head. He also made a spindle bearing preload adjuster spanner. The design isn't as well thought out as the drill mill as to adjust the bearings, you have to drop the quill out of the head, or take the motor, pulleys and their support off of the head to reach the nut.

Next week, we will be painting the last parts and I will buy a 1hp six pole three phase motor. The six pole motors run at about 1000 rpm, which with the four speeds by belt and a VFD, will give the range I require, somewhere between 150 and 3000 rpm.

Now I know that a self extracting drawbar is easy to make when I get round to it. There will be a bronze threaded sleeve with a flange at the lower end, trapped within the spindle and loctited in place.

Photos next week.

old mart11/08/2019 18:16:47
444 forum posts
42 photos


old mart11/08/2019 18:39:33
444 forum posts
42 photos

I took the camera into the museum today for the pics of the quill bearing outrigger and the nearly finished spindle. The spindle halves are awaiting the arrival of the Loctite 620. I had a rare flash of inspiration today regarding the undersize drawbar hole in the spindle. I looked in our box of reamers and found a sharp 7/16" hand reamer. I reamed from both ends of the top half of the spindle and was left with about 3" in the middle to do. I turned down 1/2" of the reamer to 8mm and found some 1/2" AF hexagon steel bar. I turned about 5" of the 6" length I cut to 11mm diameter, and drilled an 8mm hole in it. The reamer was silver soldered to the extension and the whole bore is now 7/16".

I will be sticking to my self extracting design with a bronze nut about 1" long with a 1/4" thick flange at the lower end loctited about 3/4" from the bottom of the drawbar. The flange will bear against the end of the top half of the spindle, (see the picture.

Simon Williams 311/08/2019 23:50:20
399 forum posts
65 photos

Hi again, serial number on mine is V3485, making it 1974 vintage, Your s/n at 2961 is a whole lot earlier, does this mean that Mr Senior decided to ditch needle rollers for the driven pulley and go to a bronze bush as an improvement? It does seem to indicate that my assumption that needle rollers and a spline drive is later is wrong!

Interesting stuff, what!

Like the spindle/quill.

Rgds Simon

Keep taking the tablets (out to the shed).

old mart12/08/2019 13:43:28
444 forum posts
42 photos

Miles Hellon's thread on the Tom Senior contains serial numbers against dates which I used to guess our machines vintage. As I mentioned earlier, there is no build stamp on the head to match it with the rest of the machine. As the head is a major sub assembly at least as complicated as the rest of the machine, it may well have been a completely separate build.

old mart14/08/2019 21:49:25
444 forum posts
42 photos

The spindle is now one piece using the Loctite 620. The quill and outrigger lower bearing were done up tight and Rod drilled and tapped for a 2BA grub screw to make sure nothing comes loose in the future, unless we want it to. I got a 400mm length of 7/16" 431 stainless steel for the drawbar and singlepointed the ends 7/16 UNF. I also reduced the centre part with a 0.005" cut using an insert designed for stainless, which cut beautifully. The stainless grade insets I have are halfway in sharpness between the blunt steel and the sharp aluminium type. The drawbar was too good a fit in the spindle and needed a little clearance.

I had some trouble with the bronze threaded extractor collar. I had to screw it about 1 3/8" along the drawbar and it started well with loctitite 290, but only got halfway. I had to use a hot air gun to unscrew it and start again using the 620, which just succeeded. It was also getting tight over the last 1/4". I think it must be the viscosity of the Loctite causing local heating when a long length of thread is screwed up.

old mart21/08/2019 20:53:52
444 forum posts
42 photos

I built up the spindle in the quill the other day. I gradually tightened the bearing adjusting nut, but was unsure if I had reached the point where the preload started. So I slackened off the nut and pressed the spindle to slacken off the bearings. I then set the quill on vee blocks on the bed of the drill mill and clamped it lightly with card between the quill and vee blocks and clamps. With it fixed, it was easy to creep up on the point of bearing contact and add about 10 degrees of preload.

The head is fitted on the mill and we built it up in situ. With the quill in place and locked in the up position, we figured out by trial and error how to tension the return spring. You fit the pinion shaft and connect the outer end of the spring, then carefully slide the shaft out until it just clears the rack on the quill. You can then wind it up until the od of the coils just allow the cover plate to be fitted.

I have removed the needle roller bearings from the pulley housing, as they will be easier to clean, and I want to replace the button oiler with a grease nipple. There are three sizes of button oilers on this mill, 3/16", 1/4" and 5/16".

I had to bore out the end of the motor pulley, as the current motors have a larger 24mm shaft. It couldn't be a simple job as the smallest pulley was only about 25mm at the bottom of the vee. I turned a steel bar down and pressed it onto the small end and used that as a mandrel to bore the other end. The finished wall thickness of the bored end was only 1/4", so I have fitted a collar, so the grub screws have a decent length of thread.

old mart24/08/2019 21:48:21
444 forum posts
42 photos

The head is looking nice now that it is finished except for the motor mounting. Mike fitted the bearings back in the pulley housing and fitted a grease nipple in place on the original button oiler. We don't want anyone oiling the needle rollers. I milled a second flat on the splined pulley holder, so that both of the grub screws in the pulley have something to grip on. I do wonder at the design, the whole pulley and motor assembly is held onto the head with four 2BA screws. The quill spindle drive splines are lubricated with a sparing amount of moly grease applied using a toothbrush. Otherwise, ordinary lithium grease is used for taper rollers and needle rollers. Everything else has slideway oil, except for the leadscrews, which have spray motorcycle chain gease. The quill spring causes a clang if it is let go, so I am getting some 7mm diameter o ring material to make a soft stop. I had put a step in the outrigger where it screws into the quill, for no particular reason when I turned it, and the bump stop will sit there.

old mart25/08/2019 18:41:03
444 forum posts
42 photos

I have decided to make a totally new motor mounting plate out of a 1/2" thick piece of 6086 aluminium, 250 x 153mm, as the modern mounts on the motors are quite different from the original ones. This is slightly thinner than the old one, but stronger as it is not a casting. The alternative was a 6mm thick plate as an adaptor, which was not thick enough for threading. The drawbar is fitted which is self extracting with its bronze bottom nut, and brass washer, half nut, main long nut and a second half nut at the top. Because the drawbar nut is a larger spanner size, the hole in the pulley housing which the chrome drawbar cover fitted has had to be bored out in the mill. I will have to look for something to make a cover out of, some nylon bar might do.

old mart28/08/2019 20:17:53
444 forum posts
42 photos

Today, I thought I ought to check whether my conversion to R8 has been up to scratch. With the er25 collet holder nice and tight in the spindle, using Vertex and Cutwel collets and trying 6,10,and 16mm shank endmills, the runout was 0.0003" tir on each size. Then I tried out my Osborn Titanic II, with 16mm, and 1/4" shank endmills and got 0.0005" tir on both. All the careful setting up of the spindle parts and the lower bearing outrigger has paid off. I had been worrying about how the two halves of the spindle would run, especially as the SKF lower taper roller and the Timken upper taper roller ran on different halves of the spindle. One drill chuck runs from 0.002" to 0.004" and the other larger 16mm one runs 0.004" @ 16mm, dropping nicely down to 0.001" at 6mm. The self extraction with the drawbar works very well, just 1/4 turn between pulling and pushing.

Not everything is quite as fortunate as that, however, I found out that my boring out of the motor pulley isn't deep enough, so it has to go back up on its mandrel for another 14mm of bore.

old mart04/09/2019 20:38:02
444 forum posts
42 photos

_igp2440.jpgWe aligned the pulleys the other day, the motor had to be temporarily fitted. I milled the motor shaft woodruff key down, so it was flush with the shaft od. When the pulleys were in line the grubs crews were tightened down onto the key to leave witness marks. The key was then removed and a 6mm end cutting mill was used to produce two 1.5mm deep holes in line with the witness marks. The 8mm grub screws had their tips turned to 6mm to locate in the key for a more secure drive. We don't have any means of making a key slot in the pulley, and the original wall thickness after boring it to 24mm was marginal. I had to drill and tap the key to get it out, that's what the threaded hole is for


old mart07/09/2019 19:38:01
444 forum posts
42 photos

The motor is mounted, not without slight problems. I bought a metre of the 10mm link belt, similar to Fenner nut link. Judging from the length of the old belt, I got two from the metre length, one slightly longer than the other. After fitting the longer one, I recon that the shorter one might just fit too. Fitting the link belt caused a problem straight away, we couldn't get it between the housing and the largest pulley on the spindle. I had thoughts of grinding away at the tight area in the housing, but tried an easier solution first. Taking the pulley off and reducing the top flange of the largest vee. I took off 0.042" off the diameter, and rounded the edges, and the belt just fitted with a little help. The link belts must be a bit deeper than a plain one.

old mart08/09/2019 15:52:22
444 forum posts
42 photos

_igp2444.jpg_igp2443.jpg_igp2443.jpg_igp2442.jpgThe DRO for the quill that I bought from Arc was 1/4" wider than the old one on the drill mill. Not much, but it was worth swopping them as the TS is extremely limited for space between the lock and the depth stop. The pictures show the new DRO fitted to the drill mill and early stages of fitting the old one to the TS. Mike made a lever to lock the belt tension and we have finished fitting the motor.

We intend to make covers for the belt in 6mm polycarbonate for easy checking of the belt position. Any suggestions as how to fix them would be gratefully received.


old mart12/09/2019 20:30:56
444 forum posts
42 photos

The digital quill depth reader has been finished, I had to cut about 1/2" off one end and it was more of a challenge than I thought it would be. It wore out two new Eclipse junior hacksaw blades, and then I thought it would be a good idea to drill a hole in the bottom end. I used a new solid carbide 7.3mm YG Dream for hardsteel, it did the job, but any hss or even cobalt would have failed completely. The aluminium block in the picture looks a lot different now. The stroke of the quill is exactly 2.5". Mike made a nice cap for the projecting end of the drawbar out of two pieces of aluminium fitted together as we couldn't find anything to make it out of one piece.

The motor will have to come off and be turned round, as the wiring box comes very close to the bracing for the mezzanine, especially if the head is tilted.

Edited By old mart on 12/09/2019 20:35:02

Edited By old mart on 12/09/2019 20:43:38

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