# The Hourglass



## JimDawson (Nov 9, 2014)

*My son was tasked with building the hourglass for the Wicked Witch of the West castle scene for my granddaughter’s drama class production of the Wizard of Oz.  The drama instructor deemed **unacceptable, **the first rendition of the hourglass made from two 2-liter soda bottles .  This is a high school production BTW; not a Hollywood production, but the drama instructor wants what SHE wants.
*

* 
I can’t decide if this is the drama instructor or the Witch.**


So on to plan B…..

My son found some wine bottles that had about the right shape when stacked neck to neck, but the necks are about 2 inches too long, so the problem is how to cut the bottles down to size and get them exactly correct.

  Here is what we came up with:

We have a milling machine, and it's just glass, right. *:thinking:*  First mount the MDF backing plate on the mill

*

*

Mill a pocket 0.125 deep to locate the bottle base.  Vacuum up the MDF dust as it’s cutting

*

*


Pocketing the hole for the plywood bottle hold down.  This one had to manually vacuumed because of the next operation.  Just a couple of deck screws securing the plywood to the MDF base for this operation.  20 IPM, 0.25 DOC, and 3500 RPM.  Straight flute, ½ inch carbide router bit.
*

*

Plunge milling the mounting holes 1 ½ inches deep, using the router bit.  The vacuum head would not clear for this operation.

I had already set Y-axis to zero on the center of the T-slot, so no danger of milling into the table.*:bitingnails:
	

		
			
		

		
	


*

The completed bottle holding fixture*

*

To get tool clearance we had to shorten the bottle neck a bit, so we scored the neck about ¼ inch long with a diamond wheel in the Dremel, and just popped it with a steel rod to knock it off. **We got lucky, it didn’t shatter and broke about where it was suppose to. *hew:  *The real challenge was trying to figure out where the center was in a out of round bottle neck.
*


*The HF air die grinder mounted in the endmill holder.http://www.hobby-machinist.com/show...ill-Spindle?highlight=50,000+rpm+mill+spindleThe diamond is the 5 for $5 HF wheels. It worked great, as well as the $17 Dremel wheels.*

*

The blast shield, ¼ inch Lexan.
*


*We ran a profile routine to make the cut, using a 0.004 stepover.  The tool was never working hard, and the wheel was like new after cutting two bottles.  Feed was 10 IPM, and the wheel was spinning at maybe 30,000 RPM or so.  At about 90% through the cut, the piece popped off and we let it finish to polish the top, and take off a couple of high spots.  Mist coolant is WD-40.  This also kept it wet so there was no glass dust flying around.  It took about 20 minutes to make the cut.*


* 

Setting up to do the bottle pocket in the top and bottom base.  I love my laser edge/center finder for non-critical work.  It’s good to +/- a couple of thou.

*

*

Just to illustrate the hold down for this operation.  A deck screw in each side ‘’clamp’’ is enough to hold the part.
*



*Pocketing 1/8 deep for the bottle base.  20 IPM, 0.125 DOC, 3500 RPM, 0.200 stepover*


*


Turning the acrylic plug to go between the bottles.  This will be siliconed in place on final assembly.  There is a tapered hole through the center for that sand to run through.  This will be a fully functional hourglass, complete with Wizard of Oz red sand.  I haven’t heard yet what the time specification is so we made the hole a bit small, and can adjust it later.

*

*

The plug installed. And yes, the necks have different ID’s so that step is not the camera angle.

*



*Stacked bottles, about 15 inches high*


*

And the finished product, almost.  Still needs a little paint

*


----------



## 12bolts (Nov 10, 2014)

nice work Jim,
Bit overboard for a school production though. The PET bottles would have been fine.

cheers Phil


----------



## JimDawson (Nov 10, 2014)

12bolts said:


> nice work Jim,
> Bit overboard for a school production though. The PET bottles would have been fine.
> 
> cheers Phil



YOU tell that to the drama instructor.  She's the one with the green face :rofl:


----------



## MikeWi (Nov 10, 2014)

JimDawson said:


> YOU tell that to the drama instructor.  She's the one with the green face :rofl:


You can bet I would have! She was waaaay out of line.  Should make it herself if she didn't like the original.  Maybe she had some idea of what his dad could do?


----------



## Flammable_Solid (Nov 10, 2014)

Very nice work!

Just send the Wicked Witch the bill for all of the machining at $200 an hour, sit back, and watch the fireworks.


----------



## Flammable_Solid (Nov 10, 2014)

Or constantly remind her of who owns the hourglass. 

When it is not returned after the performance, have some fun with the local law enforcement searching her home and car for it.


----------



## JimDawson (Nov 10, 2014)

Flammable_Solid said:


> Or constantly remind her of who owns the hourglass.
> 
> When it is not returned after the performance, have some fun with the local law enforcement searching her home and car for it.




I love it.  Maybe at the very least I can get comped a couple of tickets to the performance.  That should make my time worth about 50 cents / hour.


----------



## chuckorlando (Nov 10, 2014)

Very nice


----------



## jim18655 (Nov 10, 2014)

I think you're being a little selfish. You should have ran out to the shop, built a kiln, melted glass, and blew an hourglass for her.


Beautiful job.


----------



## JimDawson (Nov 10, 2014)

*Re: The Hourglass UPDATE*

UPDATE:  My son sent me a note that the drama teacher loved the new design.  :victory:


----------



## roygpa (Nov 11, 2014)

My daughter was in the drama group in junior high and high school. Best group she could have gotten involved with. No stage fright or fear of public speaking because of her involvement. She finally got a decent role for her last play of her senior year, and ended up with "Actress of the Year" honors. The Directors can be a bit particular. When they did Beauty and The Beast the Director wanted a special "Dying Rose" which was super expensive.

I would bet  that the kids fight over who gets to keep your hour glass!

Thanks for sharing.

Roy


----------



## Boswell (Nov 11, 2014)

I think we all owe a thanks to the Drama teacher. Without her, we would not have had the privilege to see how to work Glass on a vertical Mill. This is an Awesome build and has opened up my mind to soooooo many possibilities 

What a great build and thanks for sharing it.


----------



## eightball (Nov 12, 2014)

When I was a kid, and those bottle and glass cutters came out, My Grandmother taught me how to do it, with a string soaked in kerosene. Just tie it where you want, light it, and just tap the smoky part when it cools.  Worked really well


----------



## billb2011 (Nov 17, 2014)

Awesome build Jim it looks great! 

Were you able to calibrate it to get an hour on it? 

I always felt a little guilty when helping my kids with school projects, even though I always tried to let them do as much on their own as possible they still always turned out considerably better than the average elementary school kid could do on his own lol. I like going to the science fair and guessing which kids dad has a nice shop at home, its not hard to tell haha.


----------



## JimDawson (Nov 17, 2014)

billb2011 said:


> Awesome build Jim it looks great!
> 
> Were you able to calibrate it to get an hour on it?
> 
> I always felt a little guilty when helping my kids with school projects, even though I always tried to let them do as much on their own as possible they still always turned out considerably better than the average elementary school kid could do on his own lol. I like going to the science fair and guessing which kids dad has a nice shop at home, its not hard to tell haha.




Thank you for the kind words.

The scene that this is going to be used in is only a couple of minutes long, so we took a wild guess at the timing.  As it turned out, we got lucky and it's about right.  The most important aspect of this project is that is was approved by the drama class instructor.)


----------



## fgduncan (Nov 17, 2014)

Nice Job!! Nothing like using a 16" cannon to go squirrel hunting. I've used those HF diamond wheels and they are truly impressive.  Again, good job. Keep that hour glass as a momento for when they are grown up and moved away and you can relive your moment of true greatness for your grandkids.


----------



## hman (Sep 5, 2016)

Jim -

That's truly a fantastic job, and your post is very instructive.  I've built sets and props for three local community an high school theater groups for several years now.  It always seems like the neatest, most elaborate (and time consuming) pieces are on stage for the shortest times.  Ah well, that's show business!  Thanks gain for posting.  I followed the link in your post in "Shop made hold downs" to find this gem.


----------



## RJSakowski (Sep 5, 2016)

12bolts said:


> nice work Jim,
> Bit overboard for a school production though. The PET bottles would have been fine.
> 
> cheers Phil


Overboard would have been threading an internal thread on one bottle and an external thread on the other.  What a cool project!  Great woodwork too!


----------

