What do you think of this build video? Did he take a big risk?

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rwmorris
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Re: What do you think of this build video? Did he take a big risk?

Post by rwmorris »

steamingon wrote: Tue Nov 24, 2020 5:00 am Have you seen this build; https://www.youtube.com/watch?v=tdBjm5D6jxY
Wow....
Sandiapaul
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Re: What do you think of this build video? Did he take a big risk?

Post by Sandiapaul »

shild,

no probably not, but one can dream no??!
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Re: What do you think of this build video? Did he take a big risk?

Post by rkcarguy »

I'm going to say it ultimately depends on the drill bits being used and is therefore "situational".
Some drill bits start very nicely and I don't need to use a center drill. Others will try to walk/wander and you can also see the flutes of the bit flexing (here comes a triangular hole). When that happens I have to drill undersize and then step up to the final drill size. Most of the time, a through hole or drilled and tapped hole doesn't need to be right on. When you start dowel pinning things, then yes you want to center drill, drill, and ream as it only takes .001" out of position and the parts won't pin together.
I didn't like the gloved hand near the mill, and also I won't climb cut when there is loose parts ready to fall off. It doesn't happen often, but once you've had the loose part get sucked back into the climb cut and destroy the cutter, part, and knock the head out of tram, you won't want it to happen again.
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Re: What do you think of this build video? Did he take a big risk?

Post by FKreider »

shild wrote: Tue Nov 24, 2020 3:22 am But being that it's supposed to be professional I wonder why it's not nearly done yet?
The youtube video description states that all machining is being done by Gemini Industrial Machine which is a pretty serious outfit that does work on full size locomotives. I suspect that this engine is not complete yet as the machining is being paid for by a customer "The Steam Channel" and I am sure they are progressing as the funds allow them to.

Most live steam builds are very costly and time consuming, this one is progressing fairly fast based on the fact that many people take 20+ years to finish their engines.

https://thesteamchannel.com/844-construction-gallery

http://www.geminiindustrial.com/rail-division
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Harold_V
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Re: What do you think of this build video? Did he take a big risk?

Post by Harold_V »

rkcarguy wrote: Wed Nov 25, 2020 4:44 pm When you start dowel pinning things, then yes you want to center drill, drill, and ream as it only takes .001" out of position and the parts won't pin together.
It isn't common practice for dowel pins to be installed without line drilling/reaming the holes, both at the same time. The press hole is usually the bottom hole, which is taken to size through both elements, then the slip hole, the top member, is opened to provide the required slip fit for the dowel pin, using the proper reamer. Unless diamond pins are in use, it's beyond reason to expect a drilled hole to be on proper location, i.e. close enough for dowel pins to allow assembly.

These comments are intended for those who do work on manual machines, or are not using a jig borer. A CNC has the capability to duplicate location well enough to permit the holes to be drilled and reamed independent of one another, and allow assembly without the use of diamond pins. That's assuming a spotting drill or center drill is used to start the holes. Still, there's no guarantee that the parts will assemble.

Unless drills have a split point, or are exceedingly short, they tend to wander when starting. For that reason it's good practice to spot or center drill, which assures location. That, of course, depends on one's objective. When good work is desired, it's a good idea to use good work practice, not to achieve success by chance.

H
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Re: What do you think of this build video? Did he take a big risk?

Post by Greg_Lewis »

Harold_V wrote: Thu Nov 26, 2020 5:10 am ...

Unless drills have a split point, or are exceedingly short, they tend to wander when starting.
...
H

I noticed in the video that some of the drills he was starting were quite long in relation to their diameter. That would make me nervous even with a split point.
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Re: What do you think of this build video? Did he take a big risk?

Post by Harold_V »

Greg_Lewis wrote: Thu Nov 26, 2020 11:42 am I noticed in the video that some of the drills he was starting were quite long in relation to their diameter. That would make me nervous even with a split point.
And rightfully so. A new drill will cut on location, assuming it's allowed to start accordingly (spot drilled first), but all it takes for a drill to wander is for one lip to be dulled a little more than the other. While that usually tends towards just a bell mouthed start, it can be the cause of drill wander, and that's especially true if the work piece surface is slightly irregular. A drill will almost always take the path of least resistance, thus the need for short, sturdy drills when location is important. However, even that isn't enough when location is highly critical. That's what boring heads are for.

If case anyone doubts the ability of twist drills to wander---try drilling a 3/8" hole through several inches of material, drilling from both sides. If the holes meet on center, you've done an excellent job. They rarely will.

H
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Re: What do you think of this build video? Did he take a big risk?

Post by tetramachine »

The type of tap where the chips come out the top of the tap is called a "spiral Flute Tap". Very useful for deep holes, blind holes. There are forming taps, which deform the metal into threads. Fast like the spiral taps but NO chips, Great for blind holes, PITA materials like SS, use a forming tap.
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Re: What do you think of this build video? Did he take a big risk?

Post by vlnmkr »

I guess if you are a trained machinist with a fountain of knowledge and experience to draw on you can get deviate from recommended practice. I started out with flame cut frame that was Blanchard ground to thickness. First thing I did was pin them together with hardened .250 pins. Then I milled the top edge to make sure that it was plane and square. Most prototype erecting drawings seem to use that as a constant reference point. I then milled the the frame to accept the pedestal binders, fit and bolted them to the frame and then milled the slots in that order so I could maintain the rigidity of the frame . All holes were referenced from the edge of the frame and spot drilled before they were drilled to size or tapped with a tapping guide on my bridgeport. If you had minimal machining experience as I did, this is how I would recommend approaching this project.
I do not think the video was intended for instructional purposes, but it does give an overview of how one might proceed.
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Re: What do you think of this build video? Did he take a big risk?

Post by shild »

steamingon wrote: Tue Nov 24, 2020 5:00 am Have you seen this build; https://www.youtube.com/watch?v=tdBjm5D6jxY
Ok, I'm all caught up to where he currently is at video 55. It's the boiler and the driven axle which makes this one so tough isn't it? Anyone have another video series of a build?
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Re: What do you think of this build video? Did he take a big risk?

Post by rkcarguy »

Harold_V wrote: Thu Nov 26, 2020 5:10 am
rkcarguy wrote: Wed Nov 25, 2020 4:44 pm When you start dowel pinning things, then yes you want to center drill, drill, and ream as it only takes .001" out of position and the parts won't pin together.
It isn't common practice for dowel pins to be installed without line drilling/reaming the holes, both at the same time. The press hole is usually the bottom hole, which is taken to size through both elements, then the slip hole, the top member, is opened to provide the required slip fit for the dowel pin, using the proper reamer. Unless diamond pins are in use, it's beyond reason to expect a drilled hole to be on proper location, i.e. close enough for dowel pins to allow assembly.

These comments are intended for those who do work on manual machines, or are not using a jig borer. A CNC has the capability to duplicate location well enough to permit the holes to be drilled and reamed independent of one another, and allow assembly without the use of diamond pins. That's assuming a spotting drill or center drill is used to start the holes. Still, there's no guarantee that the parts will assemble.

Unless drills have a split point, or are exceedingly short, they tend to wander when starting. For that reason it's good practice to spot or center drill, which assures location. That, of course, depends on one's objective. When good work is desired, it's a good idea to use good work practice, not to achieve success by chance.

H
Harold, I was taught at a mold and die shop I interned for, to be able to do high tolerance work on manual Bridgeport mills. Granted we had DRO's on them, but the trick was to move the table the same direction to the hole location each time (i.e. crank the X/Y axis's wheels clockwise for example). If you went over, you cranked it backwards and then snuck up on the location again. We ran tension on the table locks to keep things tighter. Using this method, one could center drill, drill, and ream two sides of a mold, press the pins into the one side and have the two parts slip together no problem (or if it didn't, you "didn't have it"-according to the owner and foreman). Match drilling/reaming with the 2 parts stacked was for hacks lol). In this method, I would change the tools at each location and do all the processes while at the hole. Later, another shop acquired a Bridgeport EZ-Trak, which had a programable X/Y axis that would position at each hole while you manually ran the spindle and pushed the stylus button to move to the next hole. For this, I would center drill all the holes first, then change to drill and repeat, and so on.
I have a large set of number, letter, and fractional stub drills in split point that I ordered from MSC, and I love them. I keep longer versions of the same sizes as needed for deeper holes, but these are my go to drill bits.
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Harold_V
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Re: What do you think of this build video? Did he take a big risk?

Post by Harold_V »

rkcarguy wrote: Mon Nov 30, 2020 2:30 pm (or if it didn't, you "didn't have it"-according to the owner and foreman).
Need I say more?
Match drilling/reaming with the 2 parts stacked was for hacks lol).
Yes. Hacks. Or those who didn't want to make the same mold (or what ever component) a second time because of a mislocated dowel.
The hack you suggest is called insurance. Why risk failure, when there's a sure-fire way to ensure that the end result is functional?
If you went over, you cranked it backwards and then snuck up on the location again.
That's called dealing with backlash. It's no stranger to those of us who were trained on manual machines, and should be well understood by folks who use DRO's, too, as how the screw is loaded on any machine can spell the difference between success and failure. Those who ignore backlash are asking for problems, even when they use a DRO. Not so much of an issue with a CNC, as the feeds control location, but even they can have problems if the don't have ball screws, or the ball screws aren't tight.

H
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