Elderberry Steam Engine Drawings Question

[hfguy]

I'm teaching myself basic machining by building my first project, an Elderberry Engine Kit. I'm having a ball
screwing up perfectly good metal but I'm getting the hang of bit by bit. A couple of questions.
First, I'm having problems interpreting the drawing for bearing/port block.
- there is a symbol which looks like a "V" but with uneven legs, and a "64" inside the V. The symbol appears both upright and inverted.
- The spec for a tapped hole in the block is "#8-32 UNC-2B THD" My question is, what is "THD"?-
- A .4375 hole is to be bored in the block. I purchased a .4375 reamer but the closest drill I could find (at MSC) is a 11.1 mm drill which is .4370. Is that an OK drill to use for that reamer?

I'm buying tooling as I go, but this is gotta be the most expensive $60 kit I've ever done! I'm buying metal for practice peaces before using the metal supplied in the kit. I found that I needed more accuracy on my HF mini mill than I could do just by spinning the dials, so I added iGaging DROs for the X and Y axis and they work exceedingly well.

Anyway, I'd really appreciate it if one of you guys could answer my questions. Thanks much. Bob

 

[4GSR]

The "V" with a 64 over it is probably a surface finish symbol. The "THD" stands for THREAD.

As for the reamer, always select a drill bit size slightly smaller, about .010" to .015" smaller, than the reamer size.

Ken

 

[Wreck™Wreck]

Surface finish symbol, this is meaningless to you as you probably have no way of measuring it, surface finish requirements exist for several reasons.

One is that some feature of a component requires a minimum surface to function correctly, the second is to not have the vendor making the component waste time (money) putting a close finish on a feature that does not require it, for example if one looks at automotive drive line parts you may see a shaft with 2 highly finished bands at each end that accept bearing races whilst the material between is rough machined or "as forged or cast", giving such a feature a rough finish saves time.

 

[4GSR]

Wreck,

I have a calibrated finger nail I use for qualifying surface finish. Just so happens to be qualified for 63 finish. Kid you not, the inspection department at the company I worked at in my past ran me thru the test. Even wore a calibration sticker, too.

 

[ronboley]

I also bought the Elderberry kits (Steam Engine and Launch Engine) with the same intension of self teaching...along with some of the tools I thought I would need. My HF mill and lathe have the same dial issue so I added IGaging DRO's and tachometers (previous posts). So my kits are sitting in the cabinet and other projects have taken precident. I've ruined a lot of good metal as well, but also turned out a few small items sucessfully (previous posts on ball turner, motorcycle fuel metering screws).

I would love to see some pictures of your progress and descriptions as well. When I get the grand kids christmas wood toys done...and wife's jewelry pieces finished...and...and...maybe I'll get to the fun part of the Engine Kits....and have learned from someone else's progress thru the same project...

 

[hfguy]

Latest status as of Jan. 12. I've made great progress in making metal for the scrap pile. I've now made about 3 sets of bearing blocks. Bottom line is that I splurged and purchased and mounted Igauging X and Y DROs for my HF mini mill. They work terrific. I'm extremely pleased with the ease and accuracy I can achieve with them. However, I tried to save a little $$ and have been using a mag mounted indicator for the Z axis. Bad mistake. I've screwed up a number of pieces by machining that is off by only several thousandths, but off none the less and therefore unacceptable to me. After the last foul up a couple of days ago, I've decided to splurge and I ordered an Igauging DRO for the Z axis.

I figure the Elderberry will only cost me about $25K in materials and tools by the time I'm finished in 2025, but hey, I'll be ready to apprentice as an 85 year old machinist in a shop that makes elderberry engines with mini tools.