Replacement bit suggestions?

[scottp55]

Hey everyone, I cut these pictures using the starter set Onsrud 1/8" #61-040 which is described as a single flute-solid carbide straight for natural wood and aluminum. I loved the result but the bit was undersize (.123) but cut the entire letter out which a .125" did not in the vcarve preview. The Most important thing on these childrens blocks is the quality of the bottom of the pocket and the crispness(with no tear out) of the cut for the blind children. I was thrilled with the finish but now losing finish as the bit dulls. I can't count on the next bit being undersized and don't want to expand the pocket as I'm worried about teething kids chewing chips and the ASTM drop test. So ordering bits today and looking for replacement bits in 3mm or 3/32" in 1.5" OAL or shorter.Pocket is only 1.25" and text 1". Depth of cut .1-.115" in hard maple at 1.3,.5,15K. Bottom finish critical, must be superior. Whiteside has a SF straight in SC in 3/32" and will download Onsrud metric catalog, but was wondering If anybody can tell me if up or down spirals will do us better. Looking for a go to bit supplier. Thanks in advance for any help.

[hh_woodworking]

I like there bits and have good luck with them: If you can go to a smaller dia. then they also have 3 flute bit.

http://www.precisebits.com/products/carbidebits/precisebit-soft.asp

Ed

[Joe Porter]

Centurion sells an FEM bit which, I think, stands for Flush End Mill. You can see a definite straightness across the end that should give a better surface finish. As far as a bit being exactly what it claims to be in actual diameter, I don't think that will happen. I think they will always have a small tolerance on the minus side...joe

[scottp55]

Ed, Thanks they had a closeout on their .118" $6.81 bought 4 to try out. Joe, going to look up centurion FEM after cutting ,doing a cut for 2 people who are blind and agreed to help us out next week as to the ease of identification of various scripts and cut types (thick/thin, raised in pocket/vcarve,depth, etc.) It will be interesting what they pick as all I can do is close my eyes and guess. Thanks for the info, Newbie here.

[srwtlc]

Scott,

If you can use 1/8", 5/32", 3/16", or 5mm, Centurion Tools has them in a downcut FEM. These give good clean bottom cuts in pockets and keep the top edge clean. Another option if you were to buy quantity of them, would be to have a small radius ground on the outer tip. This helps with the 'scratch/swirl' that the sharp tip can cause. Obviously, the larger you can go, the more robust the tool will be and if you can run with a little less RPM, the tool will stay cooler and last longer.

[scottp55]

Thanks Scott, good to know about the scratch/swirl, doing a .25" downcut single line text test board this PM, It would be great for production if the people who are blind that are helping us thought a 1L .25" bit text was better than the pocket with the 1/8" bit, trying to crank out all the options as my Dad's picking up the protos thursday (5 hr drive) and bring them down to PA/NY line next week to meet them(5 hrs). The Desktop came with both up and down spirals in 1/4" which gives the best bottom finish? Doing design while eating but should be cutting in two hours, Anyone? Scrambling,still have to sand and oil. Thanks all. scott

[shilala]

You can lower your stepover on the flat area, Scott. Maybe just make a final cleanup pass for those areas?

[scottp55]

Hi Scott, Like Bob said I tried running the same toolpath twice and it did cleanup beautiful, so I started making a finish toolpath for each run(1pass, full depth,1.6 IPS) worked great and much faster. I also did 106 blocks tuesday and simply added a final pass thickness 0f .001 and I can't tell without magnification the difference between that and two passes in maple. Just got .186 fishtail? bits yesterday, only two days of electric storm have kept me out of shop, fried another landline phone. Thanks scott

[scottp55]

.118" fishtails from precisebits.com came in. Dad bought 8 at $6 something for the shipping break at that price. They were .117" but identical and very nice under my jewelers 10x. Looked at centurion FEM and they looked good if the 1/8" came in at .123" or smaller, can't quite use an actual .125", But now consensus is going vbit so may be non issue and wind up using these for pocket clearance on the 1" graphics. Thanks all.

[marcrunner]

Have had better luck with Downcut bits for less tearout/even surfacing, whether on the flat or on the sides of the pocket. Also took me a while to learn how to slow the cutter speed down, letting the bit "Carve". I even go as far as to reserve certain bits to be used only when the best possible cut is needed using others for the bulk jobs.

[scottp55]

Thanks Marc, only down spiral in my tool box is the 1/4" in the starter set.first time I used it it ripped all the points off the A's and W's at default settings but it was done before I adjusted it much. Will be using it on the end grain so maybe better. All bits are cool to the touch right after the run except the pointed roundovers(.25-.375") and I started slow 12K and then moved speed up during cuts and noted the letter that I made the speed change at and then compared finishes. If the bit is room temp then that's Ok ? Not seeing sawdust, always chips(tiny sometimes though" Still learning wish i had more "scrap" Time to get someone up in the attic and rafters for me.:)