# Is a small or large diameter bit better?



## jham66 (Mar 12, 2012)

1st post, hopefully not a silly question....

I am cleaning up the edges of some fairly roughly cut (chipped) melamine laminated chipboard using a flush trim router bit. I am using a straight edge under the board and removing 2mm off each edge, then using the trimmed board as the template under the un-trimmed board.

The job allows me to use any diameter bit, so the question is: 

Which bit is more suitable for the job? 
The smaller bit (1/2 or 3/8)?
or larger (3/4) bit?

Thanks in advance.... loving the forum so far, have been stalking it for months and thought I may as well join...

Justin


----------



## LMT Onsrud (Onsrud) (Jan 9, 2012)

*Bit Selection*



jham66 said:


> 1st post, hopefully not a silly question....
> 
> I am cleaning up the edges of some fairly roughly cut (chipped) melamine laminated chipboard using a flush trim router bit. I am using a straight edge under the board and removing 2mm off each edge, then using the trimmed board as the template under the un-trimmed board.
> 
> ...


Hello Justin,

The 3/4" bit would provide more surface feet per minute and have easier cutting loads...

Fred


----------



## harrysin (Jan 15, 2007)

jham66 said:


> 1st post, hopefully not a silly question....
> 
> I am cleaning up the edges of some fairly roughly cut (chipped) melamine laminated chipboard using a flush trim router bit. I am using a straight edge under the board and removing 2mm off each edge, then using the trimmed board as the template under the un-trimmed board.
> 
> ...


There is less chance of chipping using a smaller diameter bit. Laminex trim bits are between 1/4" and 3/8" dia. I use these and standard bearing bits, usually 1/4" with equal success.


----------



## Mike (Nov 22, 2004)

A good question Justin. A smaller bit diameter means you are removing less material and this will reduce tear out as Harry mentioned. There is a down side to them; smaller diameters also mean you are not evacuating the chips as quickly and generating more heat which can cause burning and require a slower cutting speed. Depending on the material 3/8 or 1/2" seem to work best for me.


----------



## OPG3 (Jan 9, 2011)

Justin, this is a subject that can get very scientific really quick! For the best torque ratio you're going to do best with a 1/2" diameter bit on a 1/2" diameter shaft. Straight cutters in 1/2" diameter are widely available and cheap. I've tested this quite a bit and my shop's general rule is cut depth should not exceed bit diameter in one pass, if you need to route 1/2" deep, use a 1/2" diameter bit/shank and at the right feed speed, you can cut it in one pass - as a maximum. Obviously, material being cut and feed speed and RPM can all affect your final outcome. If you're accustomed to metric 1/2" is approx 12.7mm. Good luck and be safe!


----------



## bobj3 (Jan 17, 2006)

Hi

For me I like using the 1/4" bit below,the down cut bit keeps the melamine from lifting up and will give me a nice clean edge without any chips outs.

Spiral Flush Trim Router Bit


#5089 1/4" 1" 1/4"

MLCS solid carbide router bits

==



jham66 said:


> 1st post, hopefully not a silly question....
> 
> I am cleaning up the edges of some fairly roughly cut (chipped) melamine laminated chipboard using a flush trim router bit. I am using a straight edge under the board and removing 2mm off each edge, then using the trimmed board as the template under the un-trimmed board.
> 
> ...


----------



## jham66 (Mar 12, 2012)

Thank you for the replies.

Another bit of information, the chipboard melamine is 16mm thick. I am not cutting the full width of the bit, just a 2mm trimming of the edge.

From what I have read so far, I will try a 1/2 inch and if I get any chip I will try the 3/8.


----------



## darsev (Feb 3, 2012)

jham66 said:


> 1st post, hopefully not a silly question....
> 
> I am cleaning up the edges of some fairly roughly cut (chipped) melamine laminated chipboard using a flush trim router bit.
> Justin


Justin,

can I ask how you cut the chipboard in the first place to get the rough edges? I work in a cabinet making factory, and while we regularly trim laminates that we glue to chipboard, we do avoid what you are trying to do. Can I suggest that you run some tests with some scraps of the melamine you are using. Identify the top and/or bottom side and after the trial cut you may very well find that one side is a cleaner cut than the other. I would also expect the smaller bit to function better than the bigger bits, but the state of the board you are using will also play a big part. Definitely several smaller passes if possible. If you have identified one side as better than another from your tests, then make sure that the face side of your panels is the correct way in the router to get the best cut. Even with all that work, you will most likely get some chips out somewhere. For those you should get some white touch-up wax to fill in the gaps. Touch-up wax is good for smaller chips - maybe up to 1mm in size.

Hope this helps,
Darryl


----------



## jham66 (Mar 12, 2012)

Hi Darryl,

The chips in the melamine were because I got the boards cut at Bunnings. Occasionally when I need to get the price down I will use them. The result of their blunt and out of true saw blade cost me about 2hrs work. Every time I have resulted to using their cut to size board I regret it and vow to never do it again. When I have larger jobs I get the cutting and edging done professionally and the result is much better! Thankfully a few chips is ok on the job I am doing and the end result looks ok.

Incidentally, one of the bearings somehow un-screwed itself from the router bit and damaged one of the pieces of board, I luckily had a spare that I could cut down. Using my fairly basic cut-off saw I got a muuuuccchh cleaner cut than Bunnings! I am now trying to convince myself that for the smaller jobs I am better off buying my own plunge track saw.


----------



## Doctor Atomo (Feb 23, 2012)

*Another plug for the Robo-Sander *

I've had good luck following patterns and flush trimming using the Robo-sander. 

The Robo-Sander is a sanding drum with a bearing attached to the bottom. You chuck it into the drill press and it follows your pattern and trims your workpiece flush.

This assumes you can bring the workpiece to the drill press and easily maneuver it. If you are building a countertop obviously this will not be the case, but with this method you can be sure of no chipout even in difficult material!

The one in the picture is 1"x3" but they come in several sizes.


----------



## darsev (Feb 3, 2012)

Justin,
Not surprised now that you told us how it was cut. The ony way you can be confident of a clean cut both sides with melamine is to use a saw with a scriber blade - not cheap... That is what would have happpened whe you got it done professionally. Usually only one side is visible, so you can hide some of the chipping.

Darryl


----------



## ggom20 (Feb 1, 2012)

Hello bigger bit, better cut.Angles...
Regards


----------



## jham66 (Mar 12, 2012)

The results were:

For speed: the bigger bit wins...... 
for chip free results: the smaller bit wins.

I am thinking a plunge saw with a track and at least a 60 tooth saw and I will avoid Bunnings and their blunt saw like the plague!!


----------



## ggom20 (Feb 1, 2012)

Hello!
IMHO:
In fact, there' s no winner, the bigger bit chips less but should go slow.
The thinnest chips more, so should take less, for same chipping but can go faster.

Had an interesting theotical discution a few weeks ago about lifting fibers in wood
posted a drawing that shows that at same depht off take, a small bit will tend to 
brake more the material, but, as you should reduce RPM for bigger bit, then should
also reduce feed to keep a correct state of the cut.

The real winner is the one that's real sharp.

I would not think a 10" 60 teeth would do better..
I did some of that work 30 years ago, just using a circular saw and then some kind of
hand planer for finishing edges.

Regards


----------



## KenBee (Jan 1, 2011)

Open up the link to MLCS that BJ posted, scroll down the page and read the description for the Compression Bit, then decide. Although if you do not route much Melamine the bit is cost prohibitive and in that case an up or down spiral bit is your best bet.


----------



## Phil P (Jul 25, 2010)

Mike said:


> A smaller bit diameter means you are removing less material and this will reduce tear out as Harry mentioned.


Sorry, Mike, but experience leads me to the exact opposite conclusion. The amount of material you remove is a function of the feed speed and depth of cut. Cutter diameter doesn't have anything to do with it.



Mike said:


> There is a down side to them; smaller diameters also mean you are not evacuating the chips as quickly and generating more heat which can cause burning and require a slower cutting speed.


That is very true, but I'd factor in a couple of other things. Smaller diameter cutters have less steel in them, so they tend to get hotter which in turn affects bearing life. They also have much smaller gullets so they clog-up under much lighter loads - meaning that you have to feed more slowly - which also increases the chance of scorches on the substrate as the bearings get hot. I've found it relatively easy to burn out a 1/4in diameter trim bit bearing - 3/4in bits run way cooler and the bearings really last a lot longer. I've also found that smaller diameter bits are more prone to unscrewing themselves - something which can ruin workpieces. Larger diameter cutters tend to load up a lot less quickly with contact adhesive as well - so you can trim longer before stopping to clean-up the bit. Where small diameter bits are useful is for getting into tight corners. Another feature of largr diameter bearings is that on coarse substrates, like particle board, they are large enough to deliver a smooth edge pretty much straight-off - small diameter bits can drop into voids in the substrate meaning that the end result can be somewhat rough.

The issue of cutter sharpness has come up. My own approach is to stick with replaceable-tip carbide cutters which I find a lot sharper than brazed carbide designs. The only other cutters as sharp are solid carbide spirals - these will feed faster but cost a lot more to use in the long term

Regards

Phil


----------



## jham66 (Mar 12, 2012)

ggom20 said:


> I would not think a 10" 60 teeth would do better..
> I did some of that work 30 years ago, just using a circular saw and then some kind of
> hand planer for finishing edges.
> 
> Regards


I ended up getting a 160mm (6") plunge track saw with a 60 tooth aluminium blade. I will try it out tomorrow. It was recommended as the saw/blade of choice for the work I plan to do.... here's hoping....


----------



## ggom20 (Feb 1, 2012)

Hello!

Had some after-thought about this melanine.

I remember now that it cuts fingers real good when nicely shaped at 90°.

I'll suggest not to forget a little 45° chamfer on sides.

Regards


----------



## markristow (May 30, 2011)

Hi Justin

The speed of the cutting edge striking the material will change depending on the diameter of the cutter, but this speed can be adjusted with the variable speed control of your router if it has the setting. You can therefore adjust the speed for any diameter cutter to reduce the heating on the cutting edge. With this taken care of, the other consideration is the amount of stress on the shaft of the bit and the shafts ability to stay strong when heated. I would suggest the bigger the shaft the better as my experience with 7mm shaft diameters they can break due to fatigue quite easily when they get hot.


----------



## jham66 (Mar 12, 2012)

Thank you everyone for the input. I appreciate the information. 

The new saw works a treat, I do still get the occasional chips, but the results are beyond what I expected so naturally, I am happy. I am still using the router to clean up the thinner trim strips when cut to length, but am glad to not have to do every single cut!

I am using the melamine to build snake enclosures, I have just finished off a few templates to router the air vent holes. This job was previously done by measuring up and using a jigsaw. Should cut the time taken in half! 

I have repaired an old router also, so I am going to set that one up in a router table. I may even make a track slide so I can clean up the trim edges.


----------



## darsev (Feb 3, 2012)

ggom20 said:


> I would not think a 10" 60 teeth would do better..
> I did some of that work 30 years ago, just using a circular saw and then some kind of
> hand planer for finishing edges.
> 
> Regards


Gerard,

I work with laminates such as melamine on a daily basis and what worked even a few years ago no longer works. Current laminates are tougher and much more resistant to water etc. etc. etc., but one of the side-effects is the chipping that we have been discussing. A good sharp blade will give a good clean edge on one side of the cut, and chipping to various degrees on the other. (The side closest to the blade arbour will have the chipping, which will be the top side on a hand held circular saw and the bottom side on a table saw.) The panel saws at work all have scriber blades to get around this issue (a small counter-rotating blade in front of the main blade) but we are having "discussions" with with one of the occasional saw users who forgets to use the scriber. The end result is that we have to recut the jobs again. I know the melamine from 30 years ago, and by comparison it was little more than a plastic wrap over the board, and a lot easier to get a good clean cut.

I have been intending to run some experiments cutting laminates in different ways using my home saws/router to work out the easiest/best way to get a clean cut, but haven't got that far yet. At the workshop we drill through the laminates with sacrificial boards on the other side and that leaves a clean edge on the hole. I want to try something similar with the table saw to see if that puts a clean cut on the side that normally gets chipped.

What I have also found with routing laminates is to make the first pass a lot shallower compared to routing solid timber. If you have a look at the cut edge of a laminate, you can see the glue impregnating into the chipboard/mdf for about 2mm. That is the hardest part of the whole board, so I usually make my first pass to go just through the glue layer, and then the next pass is a lot deeper and easier, almost to the opposite glue layer. Took me a while to figure this out...

BTW re your comment about sharp edges, I use gloves to handle the cut pieces all the time to stop getting cuts on my hands.

Darryl


----------



## Phil P (Jul 25, 2010)

darsev said:


> ......what worked even a few years ago no longer works. Current laminates are tougher and much more resistant to water etc. etc. etc., but one of the side-effects is the chipping that we have been discussing. A good sharp blade will give a good clean edge on one side of the cut, and chipping to various degrees on the other. (The side closest to the blade arbour will have the chipping, which will be the top side on a hand held circular saw and the bottom side on a table saw.)


I'm glad that someone else has noticed this. 10 to 12 years back when I bought my first plunge saw (Bosch) it really was possible to get an almost chip-free finish on cuts - with the modern stuff that is a lot more difficult to achieve even with a newer generation of saw and better blades. 

Regards

Phil


----------



## OPG3 (Jan 9, 2011)

> I am using the melamine to build snake enclosures, I have just finished off a few templates to router the air vent holes. This job was previously done by measuring up and using a jigsaw. Should cut the time taken in half!


Justin, I keep snakes also. I've been collecting snakes since May of 1961. What types of snakes do you keep? If you're on FaceBook - you can see some of my photos in the "Reptile Collection" photos. About 20 years ago, I commissioned a cabinet shop to build a room-full of cages - using melamine. Melamine makes a nice-looking cage, but for numerous other reasons - I am no longer using it. I later settled on Corian and further settled on a special concrete mix. Glass will also work well for the bottoms. BTW, I am only keeping constricting snakes as of my last 25-30 years. In the past my work has included essentially every species except Sea Snakes, but now the boas and pythons fit my schedule and needs quite nicely. Since the early 1990's I've also had good success in breeding several of the species.


----------



## jham66 (Mar 12, 2012)

At the moment I only have one pair. A male normal Bredli (morelia spilota bredli) and a female hypomelanistic bredli. This its the second year they have bred. Last year 21 hatchies, this year 19. We cannot keep exotics over here so every species that is commonly kept in the US (apart from aussie snakes) is illegal to keep.


----------

