need special round over bit

[dana_swift]

Does anybody know where to get a round over bits that comes to a point? With a given radius.. (I am looking for a 0.5" radius bit with a 0.25" roundover) and a slight flat at the tip to keep the bit from chipping.

The idea is to use flute toolpaths located next to each other to create beading.

I have attached a quick drawing of the profile I am looking for.

Somebody must make one.. help!

D
11176

[billp]

Dana,
Eagle America has a few;
http://www.eagleamerica.com/product/v139-0202/ea_-_roundover
139-0702 1/4" 1/2" 3/8" 1-3/4" 1/4" $19.95

[gene]

Also try magnate.net i think its called a point cutting round over

[mmason]

Hi Dana I use http://magnate.net/ They have the size you are looking for.
Works great for roping but you may want to use there side cutting bit if you want to reed a post. The tip breaks off when reeding.

[knight_toolworks]

also amana sells them if you want to get them locally.

[bleeth]

Dana:
In addition to Amana Whiteside also makes plunge roundover bits. They both have a flat section between the roundover. I believe Whiteside has a bit that size with a smaller flat area than Amana.

[chiloquinruss]

I don't have pix handy but I have used the Eagle bits just like those you are seeking. I have used them in my modeling to simulate log cabin walls and most recently an old west fort. For best results i found that I had to feed just a little slower than my normal feed rates as the bit seemd to get hot pretty quict. I think it's due to its very small tip surface. If you had a lot to do you might make a multi path toolpath where you first v carved then did a finish cut with the new bit. Have fun., Russ

[dana_swift]

Thanks guys! I appreciate how well my need was understood!

I have checked those links each of you provided.. I was getting nothing from google searches except manual round over bits with bearings and all.

I will get some bits on order now..

This forum is amazing and a huge asset!

Thanks again!

D

[myxpykalix]

This forum is amazing and a huge asset!

As "el-kabong" would say: "Aaaaand don't you fer-git it"

I'm sure most you older guys get the reference....

[archis]

On the subject of roundover bits I have a couple of newbie questions.

I'm looking for a bit that will plunge, profile cut 3/4 inch material and will leave a 1/8 roundover on the parts cut out.

What bit would you guys recommend? Finally, how do you figure out the spindle speed and feed rate when the bit manufacturer does not supply any information?

Dana - Sorry for the hijack

Jim

[dana_swift]

Jim-

Maximum feed rate is dependent on RPM, number of flutes, and strength of the bit. almost exclusively. Below the maximum, there is a zone where the finish quality improves. Below that you risk starting a fire.

Depth of cut/pass is determined by the bit geometry, material density, finish quality, and horsepower in your router/spindle.

If you have a very specific need you may need a custom bit. The round over bits this thread directed me to will plunge just fine, getting a CEL greater than 3/4 may be a trick, as a 0.125 roundover will be on a 0.250 shaft and will probably flex a great deal trying to eat 3/4 (unspecified) material, unless the material is about as dense as foam.

You may want to call Centurion and get a custom bit with a 0.5 shaft 1.0 CEL and 0.125 roundover with a plunge geometry. I have gotten custom bits from them several times and they have been amazingly fast and made exactly what I needed. They have usually required I buy a minimum number bits tho.. which is good for both parties as it leaves me with spares on hand.

The roundover bits everyone has directed me to, (now I knew what to ask for) were located in stock at the local Woodcraft store. I bought a bit, and finshed the job hours after my original post. That was on a Sunday on a holiday weekend!

Thanks all- that was very appreciated-

D

[garyb]

I'm looking for a bit that will plunge, profile cut 3/4 inch material and will leave a 1/8 roundover on the parts cut out. Onsrud 40-50
Has a 3/16 radius for 3/4" stock. doubt you will find a 1/8" radius for that size of plunging round overs

Gary

[archis]

Dana,

What is CEL?

I'm sure my project can be handled by a stock bit, I am after all a total newbie:)

For future reference approximately how much do custom bits cost and what are the quantity requirements.

[garyb]

cutting edge length

[bleeth]

Jim:

If you are after putting a small roundover on the outer edges of parts the absolute best way to do that is with a roundover bit either in a hand held router or on a router mounted in a fixed table after the parts are cut out. The single spindle CNC just isn't efficient at it at all, although many have gone after methods to do that.
The plunging roundovers mentioned below, with the exception of the series of Onsrud that Gary mentioned, are designed more for putting a bead into a solid part or for use on tool changing machines. Complete table flatness, consistancy of part thickness, and perfect bit zeroing are all critical to putting a small radius like an 1/8" on a part with your Bot.

Custom bits can be ordered 1 at a time from some companies that do it. They are not inexpensive.

Dave

[archis]

Dave,

In your opinion, does it make sense to do any rounding over on a profile cut. Say like 1/4 inch.

[bleeth]

Jim:
IMHO The Bot is not the right tool for any profile roundover on a cut through part. If one were doing something like a 3-D sign with a recessed field and wanted a roundover from the surface to the field it may make sense to program that in as part of your 3-D work, but you would probably be doing it as part of your relief work with your ball nose rather than a roundover bit.
The guys who do a lot more signage than me may have some input on this, but for simple profile cutout work I'll reach for a router every time.

Dave

[adrianm]

I use point roundover bits on the Bot to round off edges all the time. 90% of what I cut is between 50 and 200 peices out of an 8x4 sheet and it would take forever to do it by hand. Not to mention that even a brass bearing bit is too big to get into all the corners.

[bleeth]

That's interesting Adrian.
I tried it quite some time ago and was not satisfied with the results. Due to variance in ply thickness and the way mdf spoilboards never stay perfectly flat for long after surfacing I found that there were so many spots where the bit went a fraction too deep and left a ridge or not quite deep enough, regardless of how I checked and adjusted zero depth, that the amount of sanding required on the parts overcame having the bot run the radii.
Are the parts you cut required to be "furniture grade"?
Are you cutting your roundovers first and then cutting the parts out or using a combination bit like the Onsrud that Gary posted the link to?
If you are doing the profile cut first are you tabbing to hold things still with that many parts in one sheet?

Jim: If you go the custom bit route you would want your CEL from the top of the radius down to be only slightly longer than your ply so you don't cut too deep into your spoilboard. Since most ply is undersize 3/4" could be just right. Then maybe another 1/8 or so above the radius.

Dave

[adrianm]

The parts are cut from MDF (decent quality ply is hard to get and very expensive in the UK) so the thickness is usually spot on all over the board and I have a special clamping system rather than a vaccuum hold down.

All the parts are generally hand sanded by the end user before painting so slight ridges aren't a problem but I find they are quite rare anyway. Fortunately they only require the round over on the front face as flipping an 8x4 sheet full of parts wouldn't be much fun!

I machine the roundover first using a point roundover/beading bit and then run the cutout. I don't use tabs as I find the action of the down spiral bits keeps the parts in place.

[archis]

Thanks for the input guys. It sounds like I will need to experiment to see if I can get satisfactory results.

[bleeth]

MDF would make things more consistant and do-able. I think decent ply is tough to get everywhere now! I have a client who I do MDF parts for and he supplies his own raw goods. I think he is getting it from Big Orange and it has thickness variation all over, but the cabinet grades I buy for our use do have better quality control.
Hope weather is not as bad in Surrey as it is up in my family's neck of the wood in Lincoln!!

[twelchPTM]

how do you figure out the spindle speed and feed rate when the bit manufacturer does not supply any information?


many material manufactures also have recomended speeds and feeds available for there material. always remember that those numbers provided whether from the bit maker or the material supplier are only suggestions for starting pionts you will need to make adjustments on your own.