Mcmaster: Created page with " = DIY lead brick = 300 px 300 px My bricks are 6 x 2.5 x 1. IIRC they were supposed..."

2019-03-09T06:56:09Z

Created page with " = DIY lead brick = 300 px 300 px My bricks are 6 x 2.5 x 1. IIRC they were supposed..."

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= DIY lead brick =

[[File:mcmaster_pb_brick_mold_castle.jpg|300 px]]

[[File:mcmaster_pb_brick_mold_opened.jpg|300 px]]

My bricks are 6 x 2.5 x 1. IIRC they were supposed to be 6 x 3 x 1 but I didn't have big enough material on hand.

I made the molds on my Sherline 2000 CNC out of 1/8" steel slats. Bug me if you really want details, but basically I'm most likely to add details if I design new mold(s) for the actual desired brick size.

Currently takes me about 30-45 minutes a brick. Secondary mold(s) would speed this up considerably. IIRC I have material to make 4

JM setup using:
* Steel brick mold (custom)
* Lee Precision 20 Pound Pro 4 Electric Metal Melter
* Scrap lead from eBay
* Quench tray

Procedure:

[[File:mcmaster_pb_brick_mold_level.jpg|300 px]]

* Fill lead pot about 75%
* As needed, skim surface
* Assemble brick mold
* Run mold surfaces against steel cart to quickly clean them
* Run a slat through mold crevices to quickly clean those
* Place slats into bottom
* Fit top onto bottom assembly
* Verify fits together decently well (observing slats at at right angles)
* Pound the mold against a flat, hard surface. Flip over and pound the other side
* Place strap around mold and tighten

[[File:mcmaster_pb_brick_mold_in_pot.jpg|300 px]]

* Pre-heat / fill mold
* Place brick mold *into* the lead pot
** Since it was partially filled it should fit
* Initially the mold will float
* As lead fills the mold (due to sealing imperfections), adjust it as necessary to make sure it sinks to the bottom
* Should take 5-10 minutes
* If it doesn't fill, don't worry about it
* Remove mold from pot and place underneath pot at a slight angle (sprue up)
* Open lead pot. Wedge a screwdriver at top so that it stays open
* Once mold begins to overflow, remove screwdriver

[[File:mcmaster_pb_brick_mold_in_pool.jpg|300 px]]

* Final filling
* Knock off all excess lead every 5-10 seconds
* After knocking of, observe suction into sprue. If there is no more suction / solidified, you are done
* Add a small pool to the top
* If necessary, use a water squirt bottle to stop lead leaking out the back of the mold
** This will contaminate some of the lead with water, making it dangerous to throw back in
** Place all overflow into a bin to dry
* Do a final knockoff to make the sprue easier to remove

[[File:mcmaster_pb_brick_mold_quench.jpg|300 px]]

* Place mold into shallow water
** No higher than the bottom plate
* Let cool for 10 minutes
* Remove from water onto table

[[File:mcmaster_pb_brick_mold_sprue_clean.jpg|300 px]]

* If necessary, scrape off sprue excess
* Loosen clamp and slide off
* Gently tap the a side outward. Rotate through the 4 left / right + top / bottom combinations until both top and bottom are loosened

[[File:mcmaster_pb_brick_mold_open_top.jpg|300 px]]

* Remove top mold
* Sprue should give some resistance but pull out fairly easily

[[File:mcmaster_pb_brick_mold_empty.jpg|300 px]]

* Tap brick in mold against soft metal (ie aluminum) to release brick. Ensure sprue is overhanging an edge such that you aren't pounding it into the mold
* Inspect brick
* If there is a large sag at the top you cooled the brick too quickly (before quenching)
* If brick is damaged around sprue, you didn't let it cool long enough
* If the lead is not one solid piece and/or only half filled, you did not sufficiently pre-heat the mold
* Use sheet metal cutter to remove sprue
* Use a hobby knife to debur brick edges

General notes
* I usually pickup the mold by either the clamp screw or by grabbing an end (using grove joint pliers)
* I've experimented with only removing the top to reduce mold cleaning
* Full brick quenching will release lead easier but may warp mold and other issues

[[File:mcmaster_pb_brick_mold_scale.jpg|300 px]]

* Unclear if should keep/remove antimony (adds hardness)

[[File:mcmaster_pb_brick_mold_waste.jpg|300 px]]

* If excess lead may have been contaminated with water, let it dry before reusing

== Mold ==

https://github.com/JohnDMcMaster/uvscada/tree/master/ngc/pb_brick

Crude g-code generator. Think the mold may also be off by 1/8" or something like that

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Mcmaster: Created page with " = DIY lead brick = 300 px 300 px My bricks are 6 x 2.5 x 1. IIRC they were supposed..."