Clean router Edges (Mirror Edge)

[dturk]

I have a customer that brought me a phenolic/composite, He demanded to have a mirror finish on the edges of all of the cutout parts. I have been playing around with feeds and speeds, drawing resolutions, and depth of cut and I'm still unable to achieve the mirror finish.

I have run out of ideas?

One of the suggestions was to use a 3 flute Up Cut Phenolic route bit. For this router bit there seem's to be a two of options:

1. straight Knife blade
2. a chip cutter blade

I was wondering if anyone has used these bits or has solved the challenge of creating mirror finishes on phenolic composites?

[ger21]

You probably need to talk to a manufacturer of diamond tooling. And even then, a mirror finish id probably a tough task. Maybe with some type of lubricant while cutting?

Phenolic will almost instantly start to wear the edge of carbide tooling, making a really good edge difficult to achieve after the first few parts.

Try roughing the parts slightly oversized, and do a full depth finish cut with a brand new tool.

[Adrian]

I don't think you'll be able to do it without actually polishing the edge off the machine. Unless phenolic material in the US is a different thing to here in the UK.

I cut a lot as switch panels for race cars etc and it's only the top and bottom layers that have a shiny finish. The interior of the material doesn't have a mirror finish to start with so you're not going to be able to produce it with just a cutter.

[Leo]

First, if a customer demanded to me to have a mirror finish on all cutout edges, I would politely say, I am sorry but I cannot do that, and I would refuse the job.

Second, I don't know about all materials but I do know that at least acrylic can be flame polished easily.

[ger21]

Unless phenolic material in the US is a different thing to here in the UK.

There are different types of phenolic, with different "core" materials.

[dturk]

Everything that has been said so far, I definitely agree with. If it was for me, I would either flame edge the acrylic or lightly sand the edges. The carrot is that the customer wants a total of 25 completed projects, which I estimate is equal to 38 4x8 sheets of nested parts. Like all things; cost, profit, and the price is the big equalizer. I would like to have CNC solution without hiring additional help. The other big question is how real is the project (talk is cheap).

So back to the question again -- is there really a way to put a mirror finish on a solid phenolic base material??

[Rcnewcomb]

Onsrud makes a bit for polishing acrylics. It is very expensive. You might call Onsrud to see if it would work for phenolic.
Onsrud 75-130 PCD router, 1 flute, polishing

[dturk]

Randall,

Gulp - WOW that is an expensive solution. I wonder if it really works

[Samson]

The quick answer is no. Especially a cut edge.
Phenolic cores comprise of canvas, linen, nylon, paper, glass cloth, and some others.
Even using a buff system to polish, will not achieve a mirror finish.

One of the only ways to get that kind of finish on phenolic, is to put a coating on it. The finish can be polished, but a self-leveling finish should suffice.

[ger21]

You're saying both acrylic and phenolic. Which is it?

I'm not sure you can polish phenolic. And again, different types of phenolic will have very different edges.

[dealguy11]

Even if phenolic edges can be polished (I doubt it) and the expensive Onsrud bit has the ability to create a polished edge, the next question is whether your machine is rock solid enough to produce that kind of finish. Any vibration in the machine will create chatter, which will be visible on the part.

[garyb]

The tool Randal listed above is a pcd polishing tool for acrylic, which replaced the diamond polishers and falls under the hard and soft plastic category. For phenolic (composite category) the recommendation is the 66-700 Series which is a DFC upcut low helix finisher, available in 6 to 10 flute depending on diameter. these are designed to give the smoothest finish in carbon fiber materials. 8 times less in cost than an acrylic polisher
Gary

[dturk]

Looks like you guys may be right. The customer delivered the material. It looked like a phenol base plastic to me. In reality, it is High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a polyethylene thermoplastic made from petroleum. With a melting point in the range 120 to 180 °C (248 to 356 °F).

Sorry for misleading you. I guess I should stay in my own field of biochemistry instead of Petroleum Chemistry.

[martin54]

Everything that has been said so far, I definitely agree with. If it was for me, I would either flame edge the acrylic or lightly sand the edges. The carrot is that the customer wants a total of 25 completed projects, which I estimate is equal to 38 4x8 sheets of nested parts. Like all things; cost, profit, and the price is the big equalizer. I would like to have CNC solution without hiring additional help. The other big question is how real is the project (talk is cheap).

So back to the question again -- is there really a way to put a mirror finish on a solid phenolic base material??

Beware, customers like this are normally the first to complain & they will probably examine every edge with a microscope looking for the faintest of imperfections

As for the Old, I have loads of these to do, well how you deal with that is up to you but I get it a lot with vehicle livery. Customer wants a good price tells you they have 6 vans & wants a discount because he is bringing them all to you (one at a time )
So I tell them that the first 5 will be the normal single van price & I will do the last one for free

[dturk]

Martin, that is excellent advice. I take the promise (from customers) of great wealth and ton's of work -with a tongue in cheek attitude. Although, I do like your livery idea. Typically, I try to cover my development costs, equipment costs, and a small profit up front.

As far as the discussion is concerned, this has been a very interesting discussion and I don't think it is over with. I lot of good ideas have been exchanged. For example, Dealguy11 introduced the idea of vibration creating chatter. I dismissed the idea initially, due to the fact other projects did not seem to have the problem. DealGuy11's comments made me rethink the idea and I think I will create a series of sin curves and put a slow-motion camera on the bit to see if I can detect any vibration.

The recommendations of garyb also intrigued me. I'm not sure I'm going to spend the dollars to get the onshurd 66-700 bits. My friend Jim thinks someone misplaced a decimal place on the price, changing the price down from greater than 1500 dollars to under 150 dollars with discounts. Another key point (in Gary's discussion) was increasing the number of flutes to 6 -10. After a little research I found the following article:

https://www.woodworkingnetwork.com/best ... ge-acrylic

So it looks like I might have some fun and go back to the shop and run some experiments. You never know, the customer might be serious and have that kinda workload.