Resin Casting - Any Guides Or Faqs?

[angio]

I know I want to make more pens and I have plenty of ideas but the major limitation I have currently is the materials available - most commercially available blanks come in square section and my lathe currently only has a three jaw chuck. To get around this I want to make my own blanks and there appears to be plenty of people making their own but not necessarily much information on how to do so on this website. Can someone point me in the direction of guide or give me some pointers of which materials to use and where to find them in the UK?

 

Ultimately I'm looking to make two types; a transparent blank with iridescent opaque chunks in it and a laminated vacumatic style blank alternating transparnet colourless rings and opaque pearlescent/iridescent rings, both in a rod form of around 15 - 20mm in diameter.

[richardandtracy]

You could make up the equivalent of a lathe dog:

Pivot:

http://i771.photobucket.com/albums/xx356/richardandtracy/penmaking/2JawChuckPivot.gif

Pivot in the assembly:

http://i771.photobucket.com/albums/xx356/richardandtracy/penmaking/2JawChuckAssy.gif

 

It's fairly easy to make (2-3 hours max) and acts as the drive for turning long enough to turn one end down so that end can be put in a 3 jaw chuck. I actually use it with my ER32 collet chuck. I used some 20 x 20 steel square bar for the main sections and soft soldered the three parts together (soft solder is plenty strong enough up to 2000 rpm in this situation).

 

Means you don't have to make your own blanks too.

 

Regards,

 

Richard.

[angio]

That's brilliant! I still want to explore the resin casting but this set up will open up square blanks in the meantime.

 

Thanks Richard.

[richardandtracy]

I think I'm going to have to explore resin casting myself too. I want to make some pens with cnc decoration on the outside, and really need boring monochrome blanks in acrylic. I ordered 10 last week from the only place I say describing 'acrylic' blanks in the right colour. They are polyester & more brittle than I want for production pens, but it's OK for prototypes.

 

The only way I can see of getting boring monochrome acrylic consistently I can see is to cast them myself.

 

Regards,

 

Richard.

[Inspector]

For turning the square to round you should look for an independent 4 jaw chuck, each jaw turned in separately using an indicator to centre. They are the cheapest chuck you can get for a lathe (unless it has a bizarrely uncommon mount) and arguably the most useful.

 

Richard's suggestion will work nicely but is overkill for rounding a blank. Just the centre he pictured is enough with a live centre in the tailstock as long as you take light cuts and have used a centre drill in each end to provide the surface area for the friction needed to drive the blank. If you are worried about the blank spinning at the drive end or find that it does from experience you can use a traditional 4 prong spur centre or better a Steb type centre, either store bought or a version made by yourself.

 

Pete

 

 

[twissy]

I cast my own blanks using polyester resin and mica powders. As Richard pointed out though it is a very brittle material. I have made a couple of custom pens, but one of them the customer dropped and it shattered.

 

I think the bet option for custom pen making is Alumilite. I have made a few pens from blanks bought from other casters and it turns and threads beautifully. It seems very expensive over here in the UK and only available in small quantities. Not sure if the mica powders work with it or not. I believe Alumilite is a polyurethane type resin. I tried a polyurethane from Polycraft but there were so many bubbles I gave up on it.

[richardandtracy]

I have had 4 prong centres on hard plastic blanks spin on me, but have never used a Steb centre - the reason being I had scrap materials in my workshop for the 'overkill' solution, so it only cost time.

 

Looking at it, alumilite does seem pretty easy to use having seen a few videos on the Alumilite web site (see one here: http://www.alumilite.com/ProdDetail.cfm?Category=Casting%20Resins&Name=Alumilite%20Regular ). May be worth trying. It appears buying in the UK would lead to a price of about £1.65 per home cast blank (20mm dia x 125mm long) as opposed to £2.40 for a polyester blank delivered. Having colour control & not being reliant on erratic suppliers means I may investigate further.

 

Regards,

 

Richard.

[richardandtracy]

Having tried to find Alumilite in the UK and been horrified by the price, I talked to a supplier of a similar polyurethane material on E-Bay. It appears that PolyTek EasyFlo Clear ( http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=320832645805&ssPageName=ADME:X:RTQ:GB:1123 ) is somewhat similar at a slightly lower price. The curing time is a bit longer, it doesn't go opaque on curing (EasyFlo 60 does that, with a lower viscosity), and has a similar strength & viscosity to alumilite. The viscosity is low enough that with care during mixing, you shouldn't need to remove bubbles - maybe leave 6mm excess depth for any bubbles that don't have time to fully rise to the top.

 

The supplier has been kind enough to offer to send cured samples to test machinability& damage tolerance, so I shall report back later on that.

 

Regards,

 

Richard.

[linearM]

I was interested in finding out about casting blanks for pen making. I suppose it is different with each material you are casting, but I found quite a few videos on youtube. Of course I was looking for alumilite. Perhaps someone following this post could tell me why it is necessary to use a pressure kettle?

[richardandtracy]

I suspect the pressure kettle is to de-bubble the mix.

There are, I gather, two ways you can do it. The first is to use high pressure to squeeze the liquid and shrink/dissolve bubbles in the liquid before it sets. The other uses a vacuum, the pressure is lowered to the point that the bubble size expands to the point where the resin viscosity can't stop the bubble rising to the surface before the resin sets.

 

If you don't mix the resin with vigour, and the viscosity is low, then what few bubbles are entrained in the liquid should have time to rise before it sets anyway.

 

That's the theory. Will have to try the practice some time. Many years ago I did some vinyl mould casting of polyester resin for a model train. If I remember rightly, I didn't get any bubbles in the mix, but it was a long time ago & I lost interest in continuing when I went to university.

 

Regards,

 

Richard.

[richardandtracy]

I received cured samples of 4 different types of resin last night:

EasyFlo 60: White with hint of cream. Hard & glossy.

EasyFlo Clear: Less glossy, feels harder, but not quite so pleasant in the hand. Colour: yellow tinted transparent.

SG2000: Tan coloured & opaque.

One other, didn't really impinge on my consciousness as being suitable.

 

I am going to drill, tap and turn bits of each sample to see how they behave this weekend.

 

Regards,

 

Richard.

[angio]

Great, thanks for the update. I couldn't believe the cost of the alumlite.

[richardandtracy]

The PolyTek EasyFlo is cheaper, but not that much. Polyester is what I think of as 'Expensive', but it's a good deal cheaper.

 

Regards,

 

Richard.

[Inkling13]

I was just wondering what kind of lathe do you have? a wood lathe has 4 jaws, even if you didn't have chucks, you could always turn the piece round. Even with casting, as it's usually done as a slab and sawn to wdith, I don't know how you plan on getting around the square form factor by learning to cast your own blanks. I suppose that they could be cast as triangles or round, but that seems to be a whole lot of trouble for what can be solved at the root by getting a 4 jaw chuck.

 

It's like my most recent problem. I have a tap that I use for making caps, but the tap is too big for my tap holder. Instead of grinding down my tap (which I would have to do for every tap that was oversized) I just had a part made that allowed me to chuck the tap into a driill chuck. Sometimes it's easier to go to the root of the problem, instead of solve the problems individually.

[angio]

My lathe is a 1940's Myford ML4 which is a metal lathe and not a wood lathe. It came with a three jaw scroll chuck and although I intend to source a four jaw independent chuck it's not something I have got around to yet. Perhaps the biggest hurdle is that the early ml4 lathes have a different spindle nose thread to the later ml4s and finding a chuck in a usable condition this the early thread is incredibly difficult. The later thread is the same as the ML7 and there are bucket loads of those available in comparison.

 

With regards to casting non-square section, I have read of people using pipes as moulds or I could make a silicon mould. Casting square section blanks comes across as a little wasteful if you have to round off a fifth of the blank before you even start taking the material down to the final diameter. Putting it another way, if I can figure out a way of making good quality round castings, I can make five pens for every four that I could have made using square cast blanks. Just a thought. However, I do agree with you that getting a four jaw chuck is the way forward and it is something I will do because I will need one for the projects I have planned (and not just pen related ones), it's just at the moment I want to get started on making pens rather than upgrading my lathe.

 

Finally Richard's square blank adaptor could be considered overkill when there are commercially available centres that may do the job but as a new lathe user I am always looking for small projects to practice and develop my skills and even better if they have an appreciable purpose such as the pair of wicked cup oilers I made for my headstock. This is a perfect example of what I am looking for and it's a shame I didn't think of it myself.

[twissy]

It'll be interesting to hear how you got on Richard.

 

A couple of other bits of info yourself and Angio may be interested in (or already know). I reduce the viscosity of the resin by putting the cups of resin I'm going to pour in a hot water bath before adding my colourings and catalyst. This should also help with the polyurethane too. It's amazing the difference it makes especially in this cold weather. Bear in mind though that the pot life of the resin will be reduced. I have heard of people using an ultrasonic cleaner as their water bath and letting the vibrations bring the bubbles to the surface.

I have a pressure pot, but only use it when I'm casting wood and resin together. Even that is not that great, and I would really like a vacuum chamber. If you look at the videos on the Alumilite site, see how many bubbles are drawn out of the resin, it looks like it is boiling! Using the polyester resin, when casting my watch part blanks I just warm the resin and pour it, and very seldom get and air bubbles.

Regarding the colouring. Being a cheapskate, after using my first batch of water clear resin I thought that as I was colouring the resin I would only need clear. Wrong! The difference in the depth of colours was tremendous. The plain clear resin had a totally flat look to it, whereas with the water clear the effect of the metallic pigments/mica powders made the blank "pop"....visually of course :-)

 

Regards

John

[Inkling13]

I received cured samples of 4 different types of resin last night:

EasyFlo 60: White with hint of cream. Hard & glossy.

EasyFlo Clear: Less glossy, feels harder, but not quite so pleasant in the hand. Colour: yellow tinted transparent.

SG2000: Tan coloured & opaque.

One other, didn't really impinge on my consciousness as being suitable.

 

I am going to drill, tap and turn bits of each sample to see how they behave this weekend.

 

Regards,

 

Richard.

It makes me wonder what the wear characteristics of these resins are, and whether or not they are loaded with BPA. Epoxies are loaded with BPA's but I am unsure about those resins. I'd also wonder how it will hold up repeated capping and uncapping, as that is the most wear sensitive region of any pen.

[richardandtracy]

I have done a bit of machining to these resins, as shown below:

All resins drilled & tapped well. The Clear didn't squeak when being tapped, all the rest did. The thread strength was good, and no chipping occurred during tapping. I was able to get the FC6720 to spall part of the thread when removing the plug tap roughly.

When sawing samples out with a hacksaw, none melted & bound the hacksaw, unlike some acrylic resins.

The EasiFlo 60 was the only one that didn't form continuous swarf with a 6mm diameter carbide profiling tool in the lathe. The Clear was the only one to do it with a pointed carbide tool.

All polished well, however the clear had a slightly bubbly finish, and didn't polish quite as well as the others.

After turning all the pieces, I screwed them onto a 75gram mandrel and dropped them from a height of 2m onto concrete. All bounced. The Polycraft SG 2000 showed no damage. The Clear showed scuffing, while the other two showed chipping.

 

I cannot show a picture of polyester as a comparison - it didn't survive the drop and shattered into lots of bits.

 

From this, I'd suggest that the Polycraft EasyFlo Clear and SG2000 would be the better ones of the samples I tried. There is no water clear resin of this resin compound, however for solid colours either should be good, but my feeling is towards the clear at the moment because pearlescence could be used. I do not know how careful the initial cast was, so do not know how easy it is to de-bubble.

 

Regards,

 

Richard

[Michael Leaker]

If you are making your blanks with brass inner tubes, you can buy resins and moulds from the following places:

 

P Town Subbie: http://www.ptownsubbie.com/index.html

 

They have something like this:

http://www.ptownsubbie.com/images/siliconemolds/3-4Vertical_thumb.jpg

 

As well as moulds geared towards pre-fab pen kits. Also Craft Supplies USA have some supplies:

 

http://www.woodturnerscatalog.com/t/1/-/3/16/Pen-Making-Tools

 

Again, they are geared towards using pen kits though. If you are making something completely from scratch, it might not be what you want.

[dickydotcom]

I have cast resin in the past using the white plastic plumbing tube as a mould with brass end caps sealed onto the tube with candle wax.

You can Google casting resin for a supplier near you.

You can buy pearl mica from make up suppliers. Handle carefully.

 

Some methods I have used in the past:

 

Cast a block of resin and let it set. Smash it up and re-cast in resin of a different colour.

Or coat the bits in resin of a different colour then re-cast in the original colour. I did one where I re-cast before the coating had set and it bled into the final resin.

shown is one with metal powder in the coating resin.

 

Not using the tubes. I cast one colour into one of those plastic boxes that business cards come in. I then cut it into sections using wavy lines on a band saw.

I smoothed off the cut edges and put the bits back in the box and cast with a different colour resin. Then cut into straight lengths for turning.

 

Cast two colours in the same tube when wet. Very difficult unless the additives are exactly the same as you can end up with separation as one colour rises if it gets warmer than the other.

 

Using brass tubes on a kit I stuck on little pieces of acrylic, then sealed the ends of the tubes with weights inside and cast in white resin. That's the one I call tuti fruiti.

The last one is just resin with aluminium powder in it.

Dick D

 

 

 

http://i64.photobucket.com/albums/h200/dickydotcom/resincasts.jpg

http://i64.photobucket.com/albums/h200/dickydotcom/PA170003w.jpg

http://i64.photobucket.com/albums/h200/dickydotcom/aluminiumresinpen.jpg