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Featherweight 8" Straight Edge/Prism/Level/Parallel New and Improved!
I was able to wedge a melt in between rain showers yesterday. The new pattern made a good casting. Here is a 30 second video of the casting: Overview of the casting video Here are a couple stills after wire brushing the casting and cutting off risers and gates. This is a closeup of one of...- dgfoster
- Post #10
- Forum: Machine Reconditioning, Scraping and Inspection
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Featherweight 8" Straight Edge/Prism/Level/Parallel New and Improved!
Actually, I mill them on the prism faces, back and top rail if a customer requests. The surfaces are flat to less than a thou and the top and sole are parallel within a thou. That is close enough for almost everyone for prep for scraping. Milling them is pretty straight forward and I have...- dgfoster
- Post #9
- Forum: Machine Reconditioning, Scraping and Inspection
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Featherweight 8" Straight Edge/Prism/Level/Parallel New and Improved!
I am not sure I follow your suggestion. I guess you are suggesting that the casting could be ground rather than scraped or maybe the casting could be ground in preparation for scraping? Grinding would be relatively easy on this small casting. And I can see that centers could provide a means...- dgfoster
- Post #7
- Forum: Machine Reconditioning, Scraping and Inspection
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Featherweight 8" Straight Edge/Prism/Level/Parallel New and Improved!
Well, I have molded the new pattern twice and, amazing to me, it drew cleanly from the sand both times. It will require no rework though I expected it would. Over and above just pulling cleanly it pulled with no reluctance at all. That might be a little hard to explain. But patterns often...- dgfoster
- Post #5
- Forum: Machine Reconditioning, Scraping and Inspection
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Featherweight 8" Straight Edge/Prism/Level/Parallel New and Improved!
For your security, I wasn’t going to divulge the fact you ordered two (ostensibly as gifts for PM members). Please contact me offline. :D Denis- dgfoster
- Post #4
- Forum: Machine Reconditioning, Scraping and Inspection
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Featherweight 8" Straight Edge/Prism/Level/Parallel New and Improved!
And here is the mold-ready pattern printed in PETG and painted. I'll try molding it this afternoon. When trying a new pattern the sand will almost always point out some defect in the pattern that I overlooked. Usually, a bit of sanding and maybe a bit of Bondo will fix that. Denis- dgfoster
- Post #2
- Forum: Machine Reconditioning, Scraping and Inspection
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Shortening a straight edge
You know, if I were going to put it out in the barn (that presumably has a good roof) and expect it to weather a few years out there until someone shows up who wants the SE, I think I'd just paint the raw surfaces of the SE with whatever shaker can was on the shelf. Latex house paint would do...- dgfoster
- Post #5
- Forum: Machine Reconditioning, Scraping and Inspection
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Featherweight 8" Straight Edge/Prism/Level/Parallel New and Improved!
THe 8" Straight Edge I designed and started casting in January 2020 has been my top seller. Having looked at it countless times and trying to decide how it might be improved, I have just begun making new patterns for an 8 that is very similar to the original. But, I think it is a little...- dgfoster
- Thread
- Replies: 9
- Forum: Machine Reconditioning, Scraping and Inspection
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Straightening Flat Washers that Became Bowed After Tumbling
These are stamped shims, I guess. You do the stamping? and they are flat prior to tumbling? You tumble them to debur them or to texture them? The ID is? You are making ten, 100, ten thousand? lf they are so thin, how does flatness matter? Won’t they simply conform under pressure? Denis -
Nylon Tube Melting Where Riding on Steady Rest
Well, not as cast, but I thought it might be pretty easy to turn a journal between centers as is often necessary when using a standard roller or fixed finger steady. Denis -
Nylon Tube Melting Where Riding on Steady Rest
So, this is a recurring but, I guess, low volume job? I'll say it out loud, but it is probably impractical. Wouldn't an air bearing be sweet? I am thinking not a fully circumferential bearing but three pivoting pads maybe each an inch wide and 4 to 6 inches in length. For those with... -
Problem turning 4140 with HSS bits
Firmly! ;-) With the least overhang possible—-but you know that already. I assume you have optimized gibs and your toolpost is well-seated. Maybe others have some better tips…. I have seen prior discussion of inversion of cutter and mounting on the far side of the work and then there is the... -
Problem turning 4140 with HSS bits
Right, and I'm not suggesting that a light lathe can make that kind of cut. What I am getting at is that HSS can cut 4140PH and is limited not by the cutter so much as it is rigidity of the machine. It seemed like there had been a lot of chatter (not by you) about HSS being worthless or a dumb... -
Problem turning 4140 with HSS bits
I have a 1943 EE. No tubes---motor generator. Ugly paint job. Good fundamentals. Denis -
Problem turning 4140 with HSS bits
Just for fun, I went out grabbed an 1/2” piece of generic HSS and set up some 4140 pre-hard one and a quarter inch diameter in my lathe. I put it in back gear and ran at 40 rpm took and took .100 depth of cut that is .200 off the diameter and advanced at 7.5 thousand per rev. That produced a... -
Problem turning 4140 with HSS bits
I agree. But there are times when I need to make a special tool to reach in somewhere or cut a tiny groove etc and it is handy/necessary to know how to make a HSS tool unless you can afford to wait two weeks for a special carbide one to be made. As an example, last week I machined some 99.99%... -
Problem turning 4140 with HSS bits
Looks like my history was off. WWI would have been closer to the truth. BUT, the point is that long before there was HSS and common use of cemented carbides, steel was cut accurately and effectively. The Industrial Revolution began somewhere in the mid 1700's. It is a matter of proper feeds... -
Problem turning 4140 with HSS bits
I don’t think (may have missed it) the type of wheel to use in the bench grinder has been mentioned. Do not use the typical hard grey glazed piece of garbage supplied with most bench grinders. Use a soft 100 grit white aluminum oxide wheel to finish your HSS bits using the methods laid out by... -
tramming mill with brake rotor (practical machinist advertising)
I have had good results using a large 8" diameter outer race from a discarded bearing. The faces are accurately ground. An Indicol with a DTI and the job is quite quick and as accurate as the machine itself is. Once the left and right X are the same the two Y readings should then equal the X... -
Laser Straight Edge
Without getting into non-disclosure details, what is the general use of the item involved? That would imply a "Reasonable" tolerance for such use. Knowing that, better suggestions can be made. For instance, in the metrology world, there are various off-the-shelf LVDT levels and optical...