Mistakes are always there, I had a lot of wrong parts in the beginning, it became less over time but still there.
Does anyone else write out your machining steps ahead of time? ML Midge Cylinder Head
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BobsModels
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When my granddaughters started learning machining they were 8 and 10. I told them we always make the large part first that way when we muck it up we can use it to make a smaller part. Even after 48 years of model building I still start with the large part first if it makes sense. As you build different types of models you will get a sense of what needs to be built first to minimize cumulative errors. You will also learn how to redesign a part, if possible, if you make a mistake. One of the granddaughter was working on a part for about hour or so on the lathe and took it to the mill to bore a hole that could not be done on the lathe. She forgot that the lathe was direct reading off the diameter and the boring tool was off the radius. Fortunately she measured after each cut and all of a sudden it was larger than her test pin. She went to the drawings and figured out that if she moved the bolt circle out a bit, and made the mating parts flange a bit larger all would fit OK. So do not pitch to the scrap pile too quick. The other one was 16 when she worked on a part for about 8 hours and messed up the last cut. She thought of silver brazing the part, but decided to redo it, only took her 4 hours to redo and she was happier with the outcome. So just enjoy the journey however you take it. When it is all done your smile at the end result will be satisfying.
Bob
Bob
For some relatively simple jobs like replacing an oddbal size spindle with its related nut, bushings and handwheel I used to sketch an assembly with dimensions and make the components straight from the assembly sketch. However I find more and more often that when the position of a component is different from its actual machining position on lathe or drill that I start to make dumb mistakes. The worst situation is when the difference is both upside down and left-right. So more and more often I pre-think the machining steps by preparing sketches of the component in each actual machining set-up.
peterl95124
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BINGO!!!, me too, I also use a sharpie to write on the part to be machined what some of the dimensions are and double check before cutting, otherwise I tend to end up in the "measure once cut twice" club
!!!i noticed that too. Some of my sketches were flipped relative to the work and I did have to be careful
For me it was cutting gears on my mill with a dividing head. Simple as it is there was always something until I made my checklist & even then I still have to be careful!
OK, normally I don't but this will be my gift to the forum. I've stripped it out of my proprietary monster mechanical workbook. You enter data in the two green cells, answers are below in amber cells.The green bar under plate holes will shift depending on your input telling you what plate/hole circle to select. i.e. for 52 holes select plate C and set up your sectors to use the 39 hole circle. If you set it to,say, 15 holes you'll see there is a multitude of options to use for plate/hole circle. Some of the specifics in the checklist might not be generally apropos (say 2 & 3). Good Luck!
When I started my apprenticeship under my father’s watchful eyes, he made me write everything I needed to do to make a piece part. Then we would go over the list to make sure I had the proper sequence. We did this for quit sometime. It got to a point where I did not have to do the process every time. With complicated parts, yes, I would write down the steps. This was especially true when I was making boilers for myself and fellow modelers. I am 78 years old and still sketch and list my steps as needed. My personal shop time gets interrupted so many times. With the list, it gives me a point to pick up where I left off. So use that pencil and paper all you want. It is a lot cheaper than raw materials and castings. Cheers, Larry
Hi Darryl, well organized and documented! The only difference I see with my gearcutting is that I would hesitate to take 0,125" (or 3,175 mm) depth of cut in one step. Most of the times I do it in two steps, sometimes in 3 with the final cut a fine one. My gears are rather thin; a wheel with a diameter of 3,375" or about 85 mm may have a thickness of 2 maybe 3 mm. To add stiffness sometimes I can cut a pack of wheels and sometimes I clamp a thin disc between two aluminum discs. But maybe your gears are thicker or your mill is stiffer!
Thanks, Daryl! It will probably be a while before I need it, but it will be very useful.
Regards,
Charlie
I bet, apart from full depth, you weren't running at 2500rpm (dry) either. ;-D The spreadsheet just states the total end cut depth - you don't have to do it all in one pass (like I did). I was cutting wood gears for a "quicky" box joint jig for my table saw. [British machining - make the tool, to make the tool, to make the part] It could cut any size fingers, at any pitch, with any fit. You can see the X, Y & Z on the gears. They were stop positions for the box joints I was making at the time so, in essence I had to write down my sequence-steps for cutting box joints too. The clamped vertical boards were the sides of a musket case I was making.
At the extreme left below you can see the resultant box joints
Here's an overall of it finished. There was also forging, machining, stenciling, hemp rope work etc. A fun project. It holds a 75 calibre Brown Bess with all its tools, cleaning gear, shooting gear, cartridge making gear, bayonet, powder horn etc. A lot of up front CAD work to get all that to fit in nicely yet look kinda authentic.
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