I'm making disks from Wax.. thoughts?

Hello,

This is my first post here. I think that this is the right section. Please correct me if I'm wrong. I am looking for input on how I can more efficiently produce a simple part. I am making machinable wax disks from cylinders, usually in batches of 50 or more.
-The cylinders are 98mm 355mm
-the finished disk is 98mm in dia, with a 2mm step machined into both sides. The thickness can vary from 10 to 20mm. The step always results in a 10mm thick band around the circumference of the disk.



My current process is to use a cut off saw with a stop to cut them to thickness, then I user a jig on my table saw to cut in the step. This is pain staking.


I know that a lathe setup will be ideal. I am looking to purchase a lathe to make these on. I am completely ignorant on lathes. I have done some research online but I have not been able to figure out how I would hold the cylinder and make repeated cuts off of one end.


My questions are this:
-How would you guys set this up?
-Do I need to get a metal cutting lathe? Or is there a way I could jig it up on a wood lathe?

Any input would be appreciated.

Thanks!

-Greg

I'd think that slicing/shearing the wax would be better than using a saw.

You don't say how quickly you need to make these in order to be economically feasible but in general a lathe type setup would be a good way to machine the steps. Given that it's wax, almost any lathe would work though I'd want something with a 14" swing or so to keep your scale about right on a 4" diameter part.

It might be easier to melt the wax and cast it into disks. then machine the disks flat on a drill press.
You can add 25% by weight of polyethylene and then you have machinable wax. I would not want to burn a candle made with polyethylene in it though.
They do make lathes with a 4" through spindle but you are talking tens of thousands, used. Search for oil filed lathe. For your use you could make a simple lathe from two big pillow blocks and a piece of pipe. Cut with a hot wire or razor knife.
Bill D

Never worked in wax, but I would be tempted to experiment with a hot wire cutoff method, if it leaves a finish that is acceptable.

Wood lathe rpm may be challenging to your disk 'integrity'. Not sure how low they'll go nowdays. Torque should be adequate, though.

Chip

98mm/4" = ok. 355mm/9" = getting out of hand for an affordable size lathe, assuming your intending to hold any length of the stock and part it off.

You just need some custom made stuff which is faster than your current method.

You can cut off saw 9" round without rotating the stock? If so, wow. If not, use a bandsaw. Perhaps make an automatic feed sled for cheap bandsaw.

set up a router to cut the step. build or buy a powered rotary table much like a record player to spin the disk over or under a router. the disk may be held down with a overarm. a router may be swung into place with another overarm.


http://www.excitron.com/webdocs/photos/Excitron_MRT20-86-156_486_friso6.jpg

imagine a really small craptastic homemade version of this twin spindle vertical turret lathe.
the bridge could be made from 2x4's and the table plywood and a lazy suzan bearing. You press down with a swivel foot robbed from a c-clamp in the center to pinch the disk to the table. You can position your router anywhere on the beam to cut any radii you wish. You give one turn around by hand, and release the c-clamp and load another disk.

Bill D said:

It might be easier to melt the wax and cast it into disks. then machine the disks flat on a drill press.
You can add 25% by weight of polyethylene and then you have machinable wax. I would not want to burn a candle made with polyethylene in it though.
They do make lathes with a 4" through spindle but you are talking tens of thousands, used. Search for oil filed lathe. For your use you could make a simple lathe from two big pillow blocks and a piece of pipe. Cut with a hot wire or razor knife.
Bill D

Click to expand...

why not just have someone make him a bunch of two part molds and pour them? Even plastic molds can handle that kind of heat. Aluminum would cool faster. Having a dozen or so molds can produce a shitload of castings in a hurry. Use a hot knife to smooth out any irregularities after casting.

dee
;-D

dsergison said:

98mm/4" = ok. 355mm/9" = getting out of hand for an affordable size lathe, assuming your intending to hold any length of the stock and part it off.

You just need some custom made stuff which is faster than your current method.

You can cut off saw 9" round without rotating the stock? If so, wow. If not, use a bandsaw. Perhaps make an automatic feed sled for cheap bandsaw.

set up a router to cut the step. build or buy a powered rotary table much like a record player to spin the disk over or under a router. the disk may be held down with a overarm. a router may be swung into place with another overarm.


http://www.excitron.com/webdocs/photos/Excitron_MRT20-86-156_486_friso6.jpg

Click to expand...

if you insisting on machining Use a hot wire to slice and a CNC router for shaping.


dee
;-D

Thoughts ?

Apparently you haven't read other threads that go down this same path, mostly with "Arm waving"
of "I need this widjet, this big" on and on, ad nauseum.

Make a DRAWING, and apply dimensions AND tolerances.

It is the language of machinist's.... worldwide.

Then we can suggest applicable production methods.

the cylinders might be 355 mm long.

ALL QUESTIONS: give tolerances and quantity (number per unit time)

Use a wire to cut the wax.

Use a die in an arbor press to form the part. You can pay a machinist to make the die. Make sure it has an ejector.

aha!

these are the blanks for dental wax mills from the raw stock lenghts also sold here.

MachinableWax.com - Product Details | Dental CAD/CAM F-14 Green Machinable Wax Disks | GREEN 98mm Disk | Dental CAD/CAM | MachinableWax.com, Inc.

One simple way to do it might be to hot-wire the disc for overall thickness as has been suggested several times. Then use a faceplate on your wood lathe with a 98mm recess. Use the tailstock to hold the disc in the recess. Make up a toolrest / tool combination that cuts the step in one pass and to correct width and depth. Flip the part and repeat.

A little imagination and a couple hours of a machinist/fabricators time could produce the toolrest/ tool combination. Use a flat-face ballbearing "presser" in the tailstck where you would usually use a center---also not hard to dream up and make cheaply. If a central depression in the disc is acceptable (I doubt that), then a standard live center would work in place of the "presser."

Denis

I would look into the idea of casting them with molds. You can purchase mold making materials that make the process easy. This is only one possible source, there are many:

Mold Making | Alumilite Mold Making & Casting Materials

With your step on each side I would look at a flexible mold compound to make it easy to remove the casting. I would think of making a two part mold for making four or six disks at one pour. Melt, pour, wait, done. A quick knife cut to remove the sprue. With two such molds, you can be pouring the second one while the first one cools down.

4" is quite a diameter to cut with a hot wire, the kerf would solidify quite quickly behind the wire, I think.

Might want to recast the chips, but the shrink factor is going to make the castings ugly (on top at least) and they'd still need machining all over.

I think a lathe is the ticket, just not my lathe

An idea for a poor man's large spindle lathe would be to make a 'large bore hollow spindle' that runs in a roller steady rest of a small, affordable lathe. Maybe fabricate the end of this false spindle as a closing collet, with a big ass taper pipe fitting closing down on a pipe thread (with suitable slits sawn in it to make it flexible enough to squeeze the wax cylinder).

If poster would respond again and with more size requirement info (like tolerances)...I'd tell him what I think...we get too many one posters with too little info...

Hell, we don't even know if he is reading this stuff we're put'n out. Added in edit...Ahhh OK, I jumped the gun...it's only about ten hours since his first post...I'll give him this one.

I would compression mold these. wax moves around allot when melted, instead you can solid stock and shread it then compression mold it in a plastic mold. Candles and soap are made this way,
or cut the rod to length, then preheat the slug to say 100 degrees [guessing] no more than minimum needed. then put it in the compression mold to create the details. minimum heat cycle, and fast. you can heat them in a water bath, for instance a crock pot, just let the blanks float in the water for a while. doing it this way you could emboss your company name into it.

Wow! Thanks for all the replies! I did not expect this many people to chime in. Apologies for my delayed reply. I was not able to reply while at work There is some mention of my lack of information. I will do my best to speak "machinist". There are lots of things to address. I will quote, then respond to each all in one post.

GregSY said:

I'd think that slicing/shearing the wax would be better than using a saw.

You don't say how quickly you need to make these in order to be economically feasible but in general a lathe type setup would be a good way to machine the steps. Given that it's wax, almost any lathe would work though I'd want something with a 14" swing or so to keep your scale about right on a 4" diameter part.

Click to expand...

Ideally, I would like to make these as time efficient as possible. One operation would be ideal. Two would be acceptable. I also want to conserve material, but that's not as big of a deal because I can re melt the chips. I'm interested in making them faster. I make them for my work in my home wood shop. My time is relatively cheap, but I would rather be working on more interesting projects.

Chip Chester said:

Never worked in wax, but I would be tempted to experiment with a hot wire cutoff method, if it leaves a finish that is acceptable.

Wood lathe rpm may be challenging to your disk 'integrity'. Not sure how low they'll go nowdays. Torque should be adequate, though.

Chip

Click to expand...

I did not consider this as a possibility. I've done a good bit of hot wire cutting in foam (RC airplane builds. I will investigate this. I am worried that the cut will not be clean. It's worth a try though!

dsergison said:

98mm/4" = ok. 355mm/9" = getting out of hand for an affordable size lathe, assuming your intending to hold any length of the stock and part it off.

You just need some custom made stuff which is faster than your current method.

You can cut off saw 9" round without rotating the stock? If so, wow. If not, use a bandsaw. Perhaps make an automatic feed sled for cheap bandsaw.

set up a router to cut the step. build or buy a powered rotary table much like a record player to spin the disk over or under a router. the disk may be held down with a overarm. a router may be swung into place with another overarm.


http://www.excitron.com/webdocs/photos/Excitron_MRT20-86-156_486_friso6.jpg

imagine a really small craptastic homemade version of this twin spindle vertical turret lathe.
the bridge could be made from 2x4's and the table plywood and a lazy suzan bearing. You press down with a swivel foot robbed from a c-clamp in the center to pinch the disk to the table. You can position your router anywhere on the beam to cut any radii you wish. You give one turn around by hand, and release the c-clamp and load another disk.

Click to expand...

Yes! I do do it with a cut off saw. No issues spinning the stock. I've got one of those slow speed metal cutting units. I also irrigate the cut with water to keep the wax cool. Its the only way I can get a clean cut at the set RPM of the saw.

After reading threw the replies, I am now leaning toward building a purpose built router setup. I like the design you suggested.

dcsipo said:

why not just have someone make him a bunch of two part molds and pour them? Even plastic molds can handle that kind of heat. Aluminum would cool faster. Having a dozen or so molds can produce a shitload of castings in a hurry. Use a hot knife to smooth out any irregularities after casting.

dee
;-D

Click to expand...

THIS! This was my first approach! I have made a couple of different molds. I've tried a variety of pouring methods, temperatures, etc. However, I have not been able to achieve a satisfactory result. I am fighting porosity, inconsistent shrinkage (seems dependent on pour angle and speed), and bad surface quality. This is why I am leaning towards machining now.. I think that the parts are just too small to cast efficiently. I am continuing to experiment with this though, as it would be the easiest (ie semi hands off) production strategy.



Thoughts ?

Apparently you haven't read other threads that go down this same path, mostly with "Arm waving"
of "I need this widjet, this big" on and on, ad nauseum.

Make a DRAWING, and apply dimensions AND tolerances.

It is the language of machinist's.... worldwide.

Then we can suggest applicable production methods.


Yes, I am a NEWB! Apologies I did a quick drawing of the part I am making. Here are are some screen shots. Hopefully this will suffice.

jscpm said:

ALL QUESTIONS: give tolerances and quantity (number per unit time)

Use a wire to cut the wax.

Use a die in an arbor press to form the part. You can pay a machinist to make the die. Make sure it has an ejector.

Click to expand...

I am looking for a few min per unit time max. Ideally it would be seconds. Also, the tolerances are not terribly tight. I would say -+ 0.25mm or so.

dsergison said:

aha!

these are the blanks for dental wax mills from the raw stock lenghts also sold here.

MachinableWax.com - Product Details | Dental CAD/CAM F-14 Green Machinable Wax Disks | GREEN 98mm Disk | Dental CAD/CAM | MachinableWax.com, Inc.

Click to expand...

Yes! This is what I am making. Thanks!





I am beginning to think this is too long of a post.... I will continue in another one after dinner.

Thanks!

-Greg

surplusjohn said:

I would compression mold these. wax moves around allot when melted, instead you can solid stock and shread it then compression mold it in a plastic mold. Candles and soap are made this way,

Click to expand...

Very interesting John.

So with NO heat, under compression, wax will weld together ?

surplusjohn said:

I would compression mold these. wax moves around allot when melted, instead you can solid stock and shread it then compression mold it in a plastic mold. Candles and soap are made this way,
or cut the rod to length, then preheat the slug to say 100 degrees [guessing] no more than minimum needed. then put it in the compression mold to create the details. minimum heat cycle, and fast. you can heat them in a water bath, for instance a crock pot, just let the blanks float in the water for a while. doing it this way you could emboss your company name into it.

Click to expand...

I am interested in this. I think I will have to try making an new mold this weekend. It will have a plunger in it with a larger res so I can put pressure on the wax. Im mostly curious what this will do for shrinkage. Will it keep the shrinkage factor near zero? Or will it be the same. I suppose it depends on when the wax shrinks in the solidification process.

My current mold is 5% over size, but I am getting inconsistent sizes..

-Greg

Yup, keep the pressure up while it cools, feeding in molten wax to take up for the shrinkage.

Local plastic shop I was just in, runs upwards of 20k psi.....

What do the professionals do as far a maintaining a mold temp.(for wax molding)?

Keep it cooled ? Keep it warmed ?