12 Attachment(s)
Fixing plates for the lead-screw stepper and the encoder.
Hi,
the next step is to be able to attach the lead-screw stepper and the encoder. I could use Al plates to do this, which would be more "sexy", but I happen to have some 8 mm plate, a little rusty on the surface, which I like to work with. I enjoy steel fabrication, I learnt a long time ago in a quarry in Wales using an oxy-acetylene cutting torch and an ark welder. One of the things that I'd like to show in this build up is that there are other alternatives, not that I have anything against machined alloy plates, just that other things can work as well. One of the things that is important to me is to keep the lathe working, to build it's self. I have taken of the lead-screw drive mechanism and replaced it with a stepped steel plate.
Photo.1 Bare bones, where the drive gears used to be.
Photo.2 & 3 Stepped steel plates welded together and bolted on using two existing bolts and a locating dowel, not yet visible, I also added two M10 studs, nuts and spring washer to strengthen the mounting.
Photo. 4 Turning a shoulder on the lead-screw spacer to take the drive belt wheel. It was really nice to turn, not like the hot rolled I use a lot!
Photo. 5 Spacer in place on the lead-screw(I haven't fixed it yet)
Photo.6 Drilling out the toothed wheel, 30mm bit!
Photo. 7 Boring out to 36mm, to fit the spacer on the lead-screw.
Photo.8 The other side of the wheel, recessing to allow both nuts to resume their original position on the lead- screw.
Photo.9 & 10 Cutting out the motor mount.
Photo. 11 Drilling the motor mount.
Photo. 12 Today's mistake, I had planned to mount the plate horizontally, but, as I'm improvising to a large extent, I hadn't realised that the belt would not clear the mounting posts. So, cut off two corners and drilled two new holes to make it work! This might not be very clear, but in the next episode, all will become clear.
Matthew
17 Attachment(s)
Mounting posts and fixing plate.
Me again,
well, I have a lot of pics today, maybe I'm going into too much basic detail? I notice that people keep reading my entries, but I'm not getting any feed-back, so I don't know where I'm going.
Today I carried on from where I left off! First of all I made the three remaining mounting posts and then I placed the mount, drilled and tapped the support plate and bolted the whole thing together.
1. I chucked up a piece of very ordinary hot rolled steel bar, roughly 16mm in diameter, it's oval, so I turned it down until it was round, and about 15mm diameter. It isn't critical, so I wasn't very precise!
2. I centre drilled it to start the through hole.
3. The next step was to drill it through, more than 36mm,deep 4,2 mm, the threading diameter for an M5 (5mm) thread.
4. Step four was to drill out to 8,5mm, tapping size for an M10 (10mm)thread, to a depth of 25mm, long enough for the countersunk fixing bolts.
5. The M10 tap is chucked up in the tail-stock and the thread is begun manually, turning the four jaw by hand, ensuring a straight thread.
6. To continue tapping, I transferred the tap to a tap wrench, leaving the piece in the four jaw.
7. I forgot to photograph the parting cut! So the photo is an "after" shot. I had measured of 36mm and cut of the post.
8. I threaded the M5 side by hand in the vice. The tap wrench is one of the first things I made on my shaper, it's a simple design that I would recommend, the plan came from the late Art Volz on the metal shapers yahoo group.
9. The finished object.
10. Having made four posts, I clamped the assembly into place to mark the mounting holes. I could only access two of the four holes with the motor in place. I drilled through the plate with a 6,75mm bit, to mark it to place the first two bolts.
11. Once the first two threads were drilled and tapped, I could bolt the plate in place to mark drill and thread the other two holes
12. Having marked the remaining holes I preceded to drill the 6,75mm holes to 8mm to accept the bolts.
13. In this photo, I'm using the plate as a guide to thread the backplate holes.
14. This is a view of the part that you can't normally see! Just to show how it went together.
The last three pictures are self explanatory!
I hope that this is of some use to somebody!
Matthew
6 Attachment(s)
keying the lead-screw drive.
Hi!
in the original set up, the gears drove the lead-screw through the spline. The transporter that brought the lathe over the channel to me, was kind enough to bend the splined end of the lead-screw. I decided that it would be easier to use the spacer to drive the screw. I managed to straighten the lead-screw with a steel pipe and my body weight! I ended up wit 1/10mm, 0,004" of run out at the toothed wheel, which I deemed acceptable! The splined bit is about as straight as a dog back leg! The spacer had a key way in it that a grub screw keyed to the shaft. As a spacer, it didn't have much load on it, so the screw threads were adequate. I was afraid that the threads would wear, developing back lash. I had the choice between a shouldered screw and cutting a key way in the lead-screw. The shouldered screw was easiest! As I'm doing this to have threading on my lathe, I had to start with an existing thread, in the land of metric threads, whitworth is not very common! I retrieved a couple of slightly bent bolts from the gear cover that need. Too bent to chuck up, I filed the head round and sawed it to length.
i. The first photo is of the original grub screw, which would have been threads against the key-way, with "built in" back-lash.
ii. Photo N°2 just show the key-way in the spacer.
iii. N°3, the two grub screws side by side, difficult to photograph, the screw on the right was the one I made, it has a thread free 2mm that is filed to fit the key-way with no play.
iiii. The shouldered screw in place.
v. The next to last picture shows shows the toothed wheel/spacer covering half of the key screw.
vi. Finally, the two lock-nuts that adjust the end float on the lead screw. there are two steel spacers, one each side of the cast iron lug that carries the lead screw. The key-way allows adjustment.
4 Attachment(s)
finishing the leadscrew timing belt gear.
Hi,
just a small post, I've been earning my living, it takes time!
I wanted to finish off the lead-screw drive, there wasn't much to do, but, it wasn't done!
I had managed to reduce the run out on the timing belt gear to 0,1mm, / 0,004", which I deemed acceptable. The thing that remains to be done is to bolt the gear to the spacer, completing the drive.
1. Drill to 3,2mm, tapping size for 4mm metric thread.
2. Tap 4mm, I don't know where I put my tap wrench, so I did it with an adjustable spanner, not something that I like! I know that the tap wrench will turn up now that I don't need it!
3. Three 4mm blots with spring washers to keep things in place. I tapped each hole and bolted it as I went, so that everything fitted without alignment problems.
I didn't use a clearing bit, the thread starts in the Al and ends in the Fe, no play!
4. The last pic is of the finished drive.
I noticed that the thread has gone over the 5200 hits mark! Wow
Regards, Matthew
1 Attachment(s)
Encoder circuits, ELS etc
Hi
I'm back from a ten day spell in hospital, nothing serious, I'm now minus my appendix, I had peritonitis to go with it, but all seems well now!
Here are a few links that apply to the ELS. Although I'm making my lathe CNCable, the principal source of control will be the ELS
John Dammeyer has designed the Electronic Lead-Screw
Autoartisans ELS
John has also started a Forum here on the zone:
CNCZone ELS Forum
This is the original ELS forum
Yahoo ELS group
The .pdf below is the circuit that I used for my encoder circuits. It's from John's site, I suspect that if it doesn't work it's my fault! The ELS doesn't need the quadrature encoder, just one pulse per revolution.
I've started work on the cross slide limit switche, but I haven't done enough to start writing it up yet. I hope to be a bit more active in a couple of days! I'm itching to get back to it.
Regards, Matthew
8 Attachment(s)
Cross slide limit switch.
Hi,
well, I'm getting a bit more active now, so it's time to start the
cross slide limit switch write up.
I was going to write this as one piece, but it seems like a lot of photos so it'll be in two halves. Another episode tomorrow!
As an electrician, I am in favour of single limit switches where feasible as, the fewer the breaks in the line the better. Limit switches are wired normally closed, any break in the circuit makes the "Emergency" stop work. A nice little advantage is that one switch costs less!
My Colchester had a chip guard on the back of the cross slide (photo 1) all that remains is a rather solitary fixing screw. It's an absolute chip trap that is a real pain to clean. So to "kill" two birds with one stone, I'm making a chip guard that will as will have the adjustable stops for the limit switch.
Photo2, this is the end result without paint.
Pic. 3 is the plate that I used to make the box for the limit switch. It's 1,5mm thick which makes it more than strong enough to mount the switch. As usual, I drilled holes where the corners will be to make it easier to bend.
In the fourth photo you can see the fixing bolts that I welded to the box.
The fifth photo shows the mounting bolts with their spacers. The switch is fixed in upside-down, which is why I need the spacers this means that the lever is at the top, it would have worked the other way up, but the mechanism would have been more vulnerable.
In the sixth picture I am tapping one of the two fixing threads for the switch box. I really enjoy tapping cast iron like that, it cuts well and you "feel" easily when you've come to the bottom of the hole.
7 & 8 are of the box bolted to the carriage. The head of the trip post bolt was cot off at a height that will clear the inside of the cross feed screw cover.
13 Attachment(s)
cross slide limit switch second part
Hi,
here is the second part of the cross slide limit switch. It's fairly difficult to describe as it's well covered by the cross slide screw cover which carries the adjustable fingers that operate the limit switch.
The first image is the 1,5mm plate cut out ready to be folded, as usual, I've drilled holes in the corners to make it easier to fold.
Number two is the cover folded.
Photo three, I welded the corners as I did on the switch box, again to keep out suds and chips.
Image number four, tapping the end of the cross slide, I used the existing tapped holes, as I didn't have the appropriate Whitworth screws, I drilled them out to 5mm and tapped to 6mm.
In number five, the cover is clamped in position and a strip of 1,5mm plate is bolted to the cross slide. The the two are tack welded together.
The sixth image is of the cover, welded together, I was too lazy to get out the MIG, it's only 1,5mm. OK MIG would have been prettier!
With the cover "G" clamped in place, I drilled and tapped two more 5mm fixing holes.
Image number eight is the end of one of the two adjustable fingers that will trip the limit switch. Two six centimetre lengths of 10mm X 15 mm CRS (it could have been anything, hot rolled mild steel, brass, Al! I just happened to have that)are drilled 8mm through the 15mm side, the other way is drilled 5mm to be threaded M6, I milled a 3mm step in the end as the bolts that I had have only 10mm of thread. The stepped side is drilled out to 6mm. Finally I cut a slot using two blades side by side in my hacksaw to give a 2mm slot.
Photo number nine is of the two fingers on their 8mm rail prior to welding the rail in place.
In number ten, I've welded the rail in place. I was pleased that I didn't do any more than tack it and try it as I had to reposition it.
The last three photos are X+ limit, X in between an X-limit.
All this will be painted.
I will cover wiring later.
Regards, Matthew