Post by springcrocus on Jun 12, 2024 21:07:42 GMT
Lathe cross-slide
This might be a good time to post this.
The cross-slide on my lathe, a clone of the Denham Junior, doesn't really provide a means of mounting a vertical slide because the whole thing is too tall, although the circular tee-slot does provide direct mounting and swivelling for the compound slide. The one advantage the lathe does have, however, is the ability to remove the whole slide very quickly by undoing two coverplate screws and two leadscrew fixing screws
Needing to machine the saddle of the chimney for my loco, I decided to make a new cross-slide for my machine which would allow for direct fixing of alternative tooling and a vertical slide. The dovetail section is 1/2" high so I reckoned that the table needed to finish at 6" long by 5" wide by 1.1/4" deep. A colleague on the mainland, Simplyloco, offered me a large lump of iron that he had kicking around (thanks, John) but an even better offer came from a model engineer from Merseyside. After an exchange of PM's, this turned up in the post a few days later.
After setting up in the 4-jaw chuck on the lathe, the two faces were cleaned up and finished about ten thou oversize, them the edges were squared and finished to size in the mill. I don't have a vice large enough to mount this workpiece flat so all subsequent operations were done with the work mounted directly to the mill table. First of these was roughing out the underside, followed by milling the slots for three tee-channels with a 10mm carbide end mill. Having a table feed was an absolute godsend as this took quite a few hours of cutting.
Next, a 12mm diameter tee-slot cutter was passed up and down each channel, setting over to 1.1mm for the first pass and 2mm for the second, finishing with a 16mm wide slot. I have deliberately made the slot-spacing assymetrical to allow for a wider range of clamping solutions.
Next I drilled and tapped a large quantity of M8 boltholes, again using different patterns for greater options.
Clamping the work to machine the dovetail was always going to be problematic because it's neary as wide as my mill table. The power of the cut will be a bit too heavy for cam-button clamps. I got round this by modifting four clamps so that the tongues would fit into the tee-slots, then turning a length of angle iron into an extension of the table by bolting it to the front where the stop collars fit. I did have to dismantle the table feed operating arm to get it to fit but I was still able to use the feed by operating the lever between the microswitches.
This is the cross-slide mounted on the table and the dovetail cutter ready to do it's work. It's a left-hand cutter so I have to run the machine in reverse and cut left-to-right. John the Pump lent me the cutter for which I've had to make a mandrel because I couldn't use his 2MT mandrel. I made one with a 16mm diameter stem to hold in a collet; my mill has an R8 spindle.
Before setting up to mill the dovetail, I trammed the head. These mills are notorious for going out of alignment after heavy use in the same direction because there is no locking dowel to keep the head aligned at 90o to the table. My mill is the UK version of the Grizzly G0704. I knew it needed doing because I was getting tail-cutting when sending the tool left-to-right. After cutting the dovetail, the workpiece was offered up to the lathe to check the clearance over the centre section and a 10 thou feeler fits in there quite nicely.
The jib strip was next and I made this from a piece of 1.1/4" diameter cast iron bar, milling it down to form a flat bar 3/4" wide by 1/2" high. I set up my angle table to exactly 30o by clocking out on an angle gauge.
Next, a fence was clamped to the top, clocked square and the work fixed to the fence using a pair of engineer's clamps. The work needed to be on and off the fixture a number of times until a nice, sliding fit was obtained and this seemed the quickest and easiest way to mount the work.
The jib strip was faced to length, then a pair of recessed holed were drilled to take M5 cap screws and the jib strip lightly clamped the underside of the table. The centre of the five jib-adjusing grub screws was replaced with a long caphead screw to act as table lock. Also drilled and tapped were the two holes for the leadscrew block and the holes for the bedway cover.
And, finally, a picture of the new table ready to carry some tools. It takes less than two minutes to undo this one and replace the original cross-slide so I expect to be swapping between the two on a regular basis.
Regards, Steve
This might be a good time to post this.
The cross-slide on my lathe, a clone of the Denham Junior, doesn't really provide a means of mounting a vertical slide because the whole thing is too tall, although the circular tee-slot does provide direct mounting and swivelling for the compound slide. The one advantage the lathe does have, however, is the ability to remove the whole slide very quickly by undoing two coverplate screws and two leadscrew fixing screws
Needing to machine the saddle of the chimney for my loco, I decided to make a new cross-slide for my machine which would allow for direct fixing of alternative tooling and a vertical slide. The dovetail section is 1/2" high so I reckoned that the table needed to finish at 6" long by 5" wide by 1.1/4" deep. A colleague on the mainland, Simplyloco, offered me a large lump of iron that he had kicking around (thanks, John) but an even better offer came from a model engineer from Merseyside. After an exchange of PM's, this turned up in the post a few days later.
After setting up in the 4-jaw chuck on the lathe, the two faces were cleaned up and finished about ten thou oversize, them the edges were squared and finished to size in the mill. I don't have a vice large enough to mount this workpiece flat so all subsequent operations were done with the work mounted directly to the mill table. First of these was roughing out the underside, followed by milling the slots for three tee-channels with a 10mm carbide end mill. Having a table feed was an absolute godsend as this took quite a few hours of cutting.
Next, a 12mm diameter tee-slot cutter was passed up and down each channel, setting over to 1.1mm for the first pass and 2mm for the second, finishing with a 16mm wide slot. I have deliberately made the slot-spacing assymetrical to allow for a wider range of clamping solutions.
Next I drilled and tapped a large quantity of M8 boltholes, again using different patterns for greater options.
Clamping the work to machine the dovetail was always going to be problematic because it's neary as wide as my mill table. The power of the cut will be a bit too heavy for cam-button clamps. I got round this by modifting four clamps so that the tongues would fit into the tee-slots, then turning a length of angle iron into an extension of the table by bolting it to the front where the stop collars fit. I did have to dismantle the table feed operating arm to get it to fit but I was still able to use the feed by operating the lever between the microswitches.
This is the cross-slide mounted on the table and the dovetail cutter ready to do it's work. It's a left-hand cutter so I have to run the machine in reverse and cut left-to-right. John the Pump lent me the cutter for which I've had to make a mandrel because I couldn't use his 2MT mandrel. I made one with a 16mm diameter stem to hold in a collet; my mill has an R8 spindle.
Before setting up to mill the dovetail, I trammed the head. These mills are notorious for going out of alignment after heavy use in the same direction because there is no locking dowel to keep the head aligned at 90o to the table. My mill is the UK version of the Grizzly G0704. I knew it needed doing because I was getting tail-cutting when sending the tool left-to-right. After cutting the dovetail, the workpiece was offered up to the lathe to check the clearance over the centre section and a 10 thou feeler fits in there quite nicely.
The jib strip was next and I made this from a piece of 1.1/4" diameter cast iron bar, milling it down to form a flat bar 3/4" wide by 1/2" high. I set up my angle table to exactly 30o by clocking out on an angle gauge.
Next, a fence was clamped to the top, clocked square and the work fixed to the fence using a pair of engineer's clamps. The work needed to be on and off the fixture a number of times until a nice, sliding fit was obtained and this seemed the quickest and easiest way to mount the work.
The jib strip was faced to length, then a pair of recessed holed were drilled to take M5 cap screws and the jib strip lightly clamped the underside of the table. The centre of the five jib-adjusing grub screws was replaced with a long caphead screw to act as table lock. Also drilled and tapped were the two holes for the leadscrew block and the holes for the bedway cover.
And, finally, a picture of the new table ready to carry some tools. It takes less than two minutes to undo this one and replace the original cross-slide so I expect to be swapping between the two on a regular basis.
Regards, Steve
