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| Building the Division Master and modding my RT |
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| NickG:
John, that is exactly right, enjoying it is the only thing that matters and it's great to see you back in the shop, still turning out brilliant work and writing brilliant articles. I think some of the loco brigade at our model engineering club sneer at me at the fact I've got a fair sized lathe and milling machine and mess around with piddly little engines. Maybe they think I should be blindly following the plans and machining castings to build a 5" gauge loco that's been done a million times before. I appreciate that there's a lot of work in them and some excellent workmanship but I get more enjoyment messing around with small scale things and working out designs for myself. It also lets me see projects to completion (although not quickly), with only a few hours a week of workshop time there'd be no point in me starting a huge project - it wouldn't be finished until I retire! Nick |
| kvom:
I had a bigger bonehead move yesterday :hammer: although it somehow turned out OK. I was CNC drilling some 3/16" through holes (4.76mm) in a piece of 12L14 3/4" (19mm) thick. Except I "forgot" to set the drill height above the surface. So I got a rapid move (~50ipm) straight down at 1400 rpm. Somehow it punched right through and didn't even break the drill. :med: I can't claim fatigue as it was the first work of the day. |
| John Stevenson:
--- Quote from: kvom on January 12, 2011, 07:54:01 AM ---I had a bigger bonehead move yesterday :hammer: although it somehow turned out OK. I was CNC drilling some 3/16" through holes (4.76mm) in a piece of 12L14 3/4" (19mm) thick. Except I "forgot" to set the drill height above the surface. So I got a rapid move (~50ipm) straight down at 1400 rpm. Somehow it punched right through and didn't even break the drill. :med: I can't claim fatigue as it was the first work of the day. --- End quote --- Now you know your speeds and feeds for the rest of the job. :lol: |
| madjackghengis:
--- Quote from: John Stevenson on January 12, 2011, 08:59:24 AM --- --- Quote from: kvom on January 12, 2011, 07:54:01 AM ---I had a bigger bonehead move yesterday :hammer: although it somehow turned out OK. I was CNC drilling some 3/16" through holes (4.76mm) in a piece of 12L14 3/4" (19mm) thick. Except I "forgot" to set the drill height above the surface. So I got a rapid move (~50ipm) straight down at 1400 rpm. Somehow it punched right through and didn't even break the drill. :med: I can't claim fatigue as it was the first work of the day. --- End quote --- Now you know your speeds and feeds for the rest of the job. :lol: Hi John, I have to support John S. as to the feeds and speeds, it ought to go pretty fast that way though. nice looking pieces going together, makes me look forward to the day I get on the ball on that job for my rotary table. :lol: mad jack --- End quote --- |
| Bogstandard:
Sorry I didn't get this finished yesterday, I nearly got it done, but not quite, so I finished it off today. The final part to be made is the stepper mounting flange. I made this out of a bit of 12mm thick ali gauge plate. First off was to get the top and bottom parallel and to the right size. Next off I machined one of the untouched sides sqaure to the two finished ones, then it was stood up on that end to have the fourth side brought down to correct size. This is it showing the four square finished edges. Becasue the stepper actually has slightly tapered edges, I made this to a nominal size as shown on the sketch. The next job was to machine off the anodised surfaces and bring it to 8mm thick using my large flycutter. After that, I found rough centre, and marked a circle to 1mm under what is required. This will allow me to blitz to this mark, then take it steady after that to bring it to size. Using a range of drills, most of the excess material was got rid of, much quicker than boring it all the way. For me, it is easier to bore using my mill, purely because I have a power feed on the Z1 axis. Even though I only have an Imperial boring head, because I have learned to work in both standards at the same time, I find I can usually get close enough to what is required. Not bad, only 0.01mm (0.0004") out. That will be just fine, as the Loctite requires a bit of space to work. The tube fitted just right, a nice sliding, but not sloppy fit. The next bit were the four holes for stepper mounting. As I mentioned earlier, the info sheet with the stepper didn't match exactly, so I resorted to manually measuring it. Because I had made the plate spot on size all ways, it was a dead easy job to use an edge finder on two sides to find the first hole centre, then it was just a matter of moving the plate around, push up to the stop and drill. All holes ended up spot on in line with the ones in the stepper. It always pays to spend a little more time getting your base sizes correct. It was exactly the same for when the corners were rounded over, set up the first and the rest follow suit. The finished mounting plate. Everything fits OK. Before I could progress any further, the RT had to be completely built up. Correct greases and oils used in the right places, and the thrust washer underneath adjusted to give no drag or backlash. The reason for assembly was so that I could get the just made flange in approximately the right position in conjunction with the tube. The worm was engaged using the cam arrangement, and the parts marked up before being removed. Some fast acting, but high shear strength Loctite (clone) was used to join the two pieces together. I clamped it up in the vice, and went and had some lunch. It was rock solid when I got back, but for a belt and braces measure, I drilled and tapped four 4mm holes at the joint between the two. Grub screws with a little more Loctite were inserted, making sure they were below the surface when tightened. There is no way these two are going to come apart in normal use. So the assembly was finished off, and the whole lot bolted to the mill table in the normal RT permanent position. Once everything is fine tuned, I will put a piece of metalic tape over the tube access hole, just to stop swarf getting in there. This is just a quickie demo. On the third move, I noticed that the motor strained just momentarily, I think I have the worm a little too tight against the wheel, but if that is all that is wrong, I am very happy with it. This is just the way I did things. There must be dozens of other ways to mount up the stepper. Also you would have to take into account the sizes and shapes of the bits you will be trying to join together, so don't follow my actions religiously, you will most probably have to make the sizes to fit what you have got in your hands. Hope you enjoyed the journey. Bogs |
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