Preventing CA lifting and chipping

[ribanett]

Here is a different method of turning blanks for a CA finish. I was having the old problem of the CA either lifting or chipping and the little bits of coffee bean coming loose at the barrel ends until I tried this method.

I have a customer that has five coffee shops and they sell my coffee bean pens and perfume applicators. I make 25-40 items per week for this customer so time is very important and damage repair can take alot of time.

I place a disk made out of oiled card stock between the blank and bushing before I start turning.

The good points:
1. I do not have to wax the bushings, which can be a hit or miss operation.

2. I do not have to wiggle the bushing to break the bond between the blank and bushing. I think this is where most of the CA lifting comes from.

3. After I apply CA to lock the beans down, the CA between the blank and paper gives added support to the bean bits at the end of the barrel.

4. Before removing the bushings, I score a line around the blank with a knife. The paper gives me a clear reference line and prevents scoring on the blank.

The bad points: ?????

The disks are made from card stock. At first I tried standard copy paper but found out the hard way that it was too thin.


Note: I have not tried this method on wood.

The paper disks MUST be oiled. If you forget the oil, you will never get the barrel off the bushings. DAMHIKT I use Mineral Oil because there may be a reaction between other types of oil and the CA.

Apply a little oil (I use a cotton swab) just until the card stock turns translucent. Wipe off any excess oil, you should not see any oil on the surface of the card.

Here the blank is mounted ready to turn. You can see the paper disks at each end of the blank.

After turning and CA finish applied.

Here the bushings have been removed from the barrel. I insert a rod down the barrel and tap the bushings out. (one tap with a small screwdriver handle removed these bushings) As you can see, the barrel end is clean. I do not wiggle the bushings to break the bond between the bushing and barrel and I have no more CA chipping at the barrel ends.

I use this tool to remove any rough edges from the barrel

Note: Be sure to seal the ends of the blank with CA to prevent any oil transfer to the blank.

I print my disks using CAD. If you would like to try this method and do not have CAD, email me with the dia you need. I will send you back a pdf file.

Give it a try, like so many things: What works for me may not work for you. I have turned 152 pens and perfume applicators with this method with only 7 that required damage repair.

 

[CHICAGOHAND]

Thanks for the tips. My problem with the coffee blanks is that I cannot get a good consistent CA finish. These blanks are driving me crazy. Any tips there.
I don't know if the problem is the two different materials or my method of applying the CA.
Any tips would be appreciated.

 

[ribanett]

My problem with the coffee blanks is that I cannot get a good consistent CA finish. These blanks are driving me crazy. Any tips there.

Dave,
There are as many methods of applying a CA finish as there are turners using CA as a finish.

So heres mine

I use calipers to check the dia of the barrel. For a tapered barrel I use two sets

I run my lathe at about 800 rpm for a perfume applicator and 525 rpm for a Baron. These rpms give me a surface speed of about 80 feet per minute on both barrel dia. By maintaining the the same fpm I can move the CA pad across both barrels at the same speed.

I use both thin and med CA and accelerator.

I tried a number of brands with poor results until I started getting it from Monty. I bet he mixes it himself in a caldron in a dark cavern somewhere while wearing a pointed hat and long flowing robe, with a pack of mean dogs guarding the place when he's not there.:biggrin:

Monty stocks two strengths of accelerator, strong and mild. Tried the strong first and was not happy with the results. The mild gives me a great finish.

I apply the CA using strips of blue shop towels. I cut it into strips about 0.75" wide and 5" long and fold it twice. I can apply four coats with each strip and it is a good way to keep track of how many coats I have applied.

How much CA to put on the pad comes from trial and error. I have done it so many times that I look at the blank and know how much to put on the pad. A Baron will take alot more than a slimline.

With thin CA I make one pass per coat, first from left to right. The next coat from right to left and so on.

With med CA I make two passes per coat, again starting from each end of the blank.

I apply a VERY LIGHT misting of accelerator after each coat of CA and wait about a minute.

How fast to move the pad comes from trial and error. I move the pad fast enough to prevent the curing CA from grabing it, yet slow enough to smooth out the ridges in the CA

Rough the blank down to about 0.150 oversize and apply two coats of thin CA to lock in the beans. Take it down 0.070 and apply two coats of CA and again at about .015 oversize.

Tool the blank down to 4-5 thou oversize and apply two coats of thin CA and one coat of med CA, then using 220-320-600 dry sandpaper, take it down to 3-4 thou undersize to allow for the CA buildup.

Use a soft brush to remove all the dust from the surface dings and wipe down with DNA.

Apply two coats of thin CA and 4 coats of med CA.

Wet sand with 600 and light pressure, stopping after about 15 seconds of sanding.

Apply 6 coats of med CA and wet sand with 600 and 1500 to your final size.

I finish off with a polish using MAAS metal polish.

This is how I do, like I said at the beginning, just one way of a thousand.
Hope this helps

 

[PaulDoug]

Good tips. I'm going to givr yjr oilrd card a try with wood next tiem I use wood. Thanks.

 

[MoJo]

Thanks for the great instructions Larry. I am planning to turn a coffee bean pen for my wife. She loves the smell of the beans. With this in mind, can you still smell the beans with a CA finish? If not, are they too unstable to leave uncoated? Can you seal them with CA but sand to expose the beans? Suggestions appreciated...

Thanks,
Joe

 

[wolftat]

Larry, I like the idea but I just remove the bushings and finish between centers. After I finish, I hit the ends with a similar sander and I am done, it save some time.

 

[ribanett]

Thanks for the great instructions Larry. I am planning to turn a coffee bean pen for my wife. She loves the smell of the beans. With this in mind, can you still smell the beans with a CA finish? If not, are they too unstable to leave uncoated? Can you seal them with CA but sand to expose the beans? Suggestions appreciated...

Thanks,
Joe

My customer had the same idea a couple of week ago. I made her ten test pens (Sierras) with a uncoated band about 3/4" wide at the top of the clip. She is testing them with her managers and I am waiting for their input. The only problem I see is with the transition from the CA finish to the uncoated band. The CA is thick and there is a ridge. I have tried to sand it down but it does not look right to me but I will keep working on it.

I made one without a CA finish and it smelled great, but after time the beans where you hold the pen soaked up the oil from her fingers and turned darker than the beans on the upper part of the pen. So this is a work in progress.

 

[CHICAGOHAND]

Thanks for the reply. I have a pretty good grasp on CA finish on wood but these coffee blanks are not cooperating. Maybe the accelerator is the part of the equation that is missing.
I will keep that in mind.
I never used accelerator before because of the fact that I never had a problem with CA drying fast enough.
I will let you know of my progress.