Broken Cutting Bits when drilling holes

[63falcon757]

im working on a project and was drilling a series of holes 3/4in wide by .563 deep. the holes were not within 3.5in from the end. and i broke 2 bits one right after the other. the 1st bit was a week old, the 2nd bit was brand new. can anyone help me with this issue. 39.99 is gettn too expensive to keep buying bits every week. is there a cheaper alternative to a 1/8 cutting bit for the Carve Tight spendle? I have read some post where someone claims using rotozip bits and strait 1/4 bits, doese anyone have any experience with these. I have not tried other bits yet. I am useing the 1/8 bit to cut holes and to cut thru along a path. but i have not broken one yet during a cut thru on a path.

[63falcon757]

http://www.floormall.com/janka-rating-wood-species/cumaru-brazilian-teak-species-janka-rating.php
this was the wood that the bits broke in. is there a rating of hardness these bits are rated for? i did however put in my 3/8 strait bit to finish cutting the project. the bit did however cut the drill hole wider than i wanted. but that wasnt critical. I also used the strait3/8 bit to cut the cut thru path around the object. the project is a glued together panel of diffrent woods being cut into a longboard skateboard.

[AskBud]

http://www.floormall.com/janka-rating-wood-species/cumaru-brazilian-teak-species-janka-rating.php
this was the wood that the bits broke in. is there a rating of hardness these bits are rated for? i did however put in my 3/8 strait bit to finish cutting the project. the bit did however cut the drill hole wider than i wanted. but that wasnt critical. I also used the strait3/8 bit to cut the cut thru path around the object. the project is a glued together panel of diffrent woods being cut into a longboard skateboard.
Here is your first clue, from your own linked web site.
Woodworking Qualities: Cumaru’s inherent Density can create problems with the working of this wood. It shows the propensity to dull cutting edges, as well as the tendency to split during the nailing process. Pre-boring holes can be helpful in this. Cumaru’s sanding properties are favorable, although the acceptance of a finish is noted as problematic at times. During the sanding process, the dust produced has been reported to cause allergic reactions often.
AskBud

[63falcon757]

yeah, i kinda thought that would be the problem. i had cut this wood before in another project with no problem. so on a Janka hardness scale of 0-4000, what would be the max i would want to put in with that 1/8 cutting bit?

[lawrence]

Yup, yet another reason that speed control would be awesome-- though I'm not 100% sure even that would help in this case

That's some hard wood... darned hard... On the Janka hardness scale it's at the top of the chart
Here's some other woods for comparason...
Lawrence
Ipe (http://forum.carvewright.com/species_ipe.html) / Brazilian Walnut (http://forum.carvewright.com/species_ipe.html) / Lapacho (http://forum.carvewright.com/species_lapacho.html) 3684 Cumaru (http://forum.carvewright.com/species_cumaru.html) / Brazilian Teak (http://forum.carvewright.com/species_cumaru.html) 3540 Ebony (http://forum.carvewright.com/species_ebony.html) 3220 Brazilian Redwood (http://forum.carvewright.com/species_br_redwood.html) / Paraju (http://forum.carvewright.com/species_paraju.html) 3190 Angelim Pedra (http://forum.carvewright.com/species_angelimpedra.html) 3040 Bloodwood (http://forum.carvewright.com/species_bloodwood.html) 2900 Red Mahogany (http://forum.carvewright.com/species_redmahogany.html) / Turpentine (http://forum.carvewright.com/species_turpentine.html) 2697 Spotted Gum (http://forum.carvewright.com/species_spottedgum.html) 2473 Brazilian Cherry (http://forum.carvewright.com/species_jatoba.html) / Jatoba (http://forum.carvewright.com/species_jatoba.html) 2350 Mesquite 2345 Santos Mahogany (http://forum.carvewright.com/species_mahogany.html) / Bocote (http://forum.carvewright.com/species_bocote.html) / Cabreuva (http://forum.carvewright.com/species_cabreuva.html) 2200 Pradoo (http://forum.carvewright.com/species_pradoo.html) 2170 Brushbox (http://forum.carvewright.com/species_brushbox.html) 2135 Karri (http://forum.carvewright.com/species_karri.html) 2030 Sydney Blue Gum (http://forum.carvewright.com/species_sydneyblue.html) 2023 Bubinga (http://forum.carvewright.com/species_bubinga.html) 1980 Cameron (http://forum.carvewright.com/species_cameron.html) 1940 Tallowwood (http://forum.carvewright.com/species_tallowwood.html) 1933 Merbau (http://forum.carvewright.com/species_merbau.html) 1925 Amendoim (http://forum.carvewright.com/species_amendoim.html) 1912 Jarrah 1910 Purpleheart (http://forum.carvewright.com/species_purpleheart.html) 1860 Goncalo Alves (http://forum.carvewright.com/species_goncalo.html) / Tigerwood (http://forum.carvewright.com/species_tigerwood.html) 1850 Hickory (http://forum.carvewright.com/species_hickory.html) / Pecan (http://forum.carvewright.com/species_pecan.html) / Satinwood (http://forum.carvewright.com/species_satinwood.html) 1820 Afzelia (http://forum.carvewright.com/species_afzelia.html) / Doussie (http://forum.carvewright.com/species_doussie.html) 1810 Bangkirai (http://forum.carvewright.com/species_bangkirai.html) 1798 Rosewood (http://forum.carvewright.com/species_rosewood.html) 1780 African Padauk (http://forum.carvewright.com/species_padauk.html) 1725 Blackwood (http://forum.carvewright.com/species_blackwood.html) 1720 Merbau (http://forum.carvewright.com/species_merbau.html) 1712 Kempas (http://forum.carvewright.com/species_kempas.html) 1710 Locust (http://forum.carvewright.com/species_locust.html) 1700 Highland Beech (http://forum.carvewright.com/species_highlandbeech.html) 1686 Wenge (http://forum.carvewright.com/species_wenge.html) / Red Pine (http://forum.carvewright.com/species_pine.html) 1630 Tualang (http://forum.carvewright.com/species_tualang.html) 1624 Zebrawood (http://forum.carvewright.com/species_zebrawood.html) 1575 True Pine (http://forum.carvewright.com/species_pine.html) / Timborana (http://forum.carvewright.com/species_timborana.html) 1570 Peroba (http://forum.carvewright.com/species_peroba.html) 1557 Kambala (http://forum.carvewright.com/species_kambala.html) 1540 Sapele (http://forum.carvewright.com/species_sapele.html) / Sapelli (http://forum.carvewright.com/species_sapele.html) 1510 Curupixa (http://forum.carvewright.com/species_curupixa.html) 1490 Sweet Birch (http://forum.carvewright.com/species_birch.html) 1470 Hard Maple (http://forum.carvewright.com/species_maple.html) / Sugar Maple (http://forum.carvewright.com/species_maple.html) 1450 Coffee Bean (http://forum.carvewright.com/species_coffeebean.html) 1390 Natural Bamboo (http://forum.carvewright.com/species_bamboo.html) (represents one species) 1380 Australian Cypress (http://forum.carvewright.com/species_cypress.html) 1375 White Oak (http://forum.carvewright.com/species_oak.html) 1360 Tasmanian Oak (http://forum.carvewright.com/species_tasmanianoak.html) 1350 Ribbon Gum (http://forum.carvewright.com/species_ribbongum.html) 1349 Ash (White) (http://forum.carvewright.com/species_ash.html) 1320 American Beech (http://forum.carvewright.com/species_beech.html) 1300 Red Oak (Northern) (http://forum.carvewright.com/species_oak.html) 1290 Carribean Heart Pine (http://forum.carvewright.com/species_pine.html) 1280 Yellow Birch (http://forum.carvewright.com/species_birch.html) 1260 Movingui (http://forum.carvewright.com/species_movingui.html) 1230 Heart Pine (http://forum.carvewright.com/species_pine.html) 1225 Carbonized Bamboo (http://forum.carvewright.com/species_bamboo.html) (represents one species) 1180 Cocobolo (http://forum.carvewright.com/species_cocobolo.html) 1136 Brazilian Eucalyptus (http://forum.carvewright.com/species_eucalyptus.html) / Rose Gum (http://forum.carvewright.com/species_roserivergum.html) 1125 Makore (http://forum.carvewright.com/species_makore.html) 1100 Boreal (http://forum.carvewright.com/species_boreal.html) 1023 Black Walnut (http://forum.carvewright.com/species_walnut.html) 1010 Teak (http://forum.carvewright.com/species_teak.html) 1000 Sakura (http://forum.carvewright.com/species_sakura.html) 995 Black Cherry (http://forum.carvewright.com/species_cherry.html) / Imbuia (http://forum.carvewright.com/species_imbuia.html) 950 Boire (http://forum.carvewright.com/species_boire.html) 940 Paper Birch (http://forum.carvewright.com/species_birch.html) 910 Cedar (http://forum.carvewright.com/species_cedar.html) 900 Southern Yellow Pine (Longleaf) (http://forum.carvewright.com/species_pine.html) 870 Lacewood (http://forum.carvewright.com/species_lacewood.html) / Leopardwood (http://forum.carvewright.com/species_leopardwood.html) 840 Parana (http://forum.carvewright.com/species_parana.html) 780 Sycamore (http://forum.carvewright.com/species_sycamore.html) 770 Shedua (http://forum.carvewright.com/species_shedua.html) 710 Southern Yellow Pine (Loblolly and Shortleaf) (http://forum.carvewright.com/species_pine.html) 690 Douglas Fir 660 Larch (http://forum.carvewright.com/species_larch.html) 590 Chestnut (http://forum.carvewright.com/species_chestnut.html) 540 Hemlock (http://forum.carvewright.com/species_hemlock.html) 500 White Pine (http://forum.carvewright.com/species_pine.html) 420 Basswood (http://forum.carvewright.com/species_basswood.html) 410 Eastern White Pine (http://forum.carvewright.com/species_pine.html) 380

[DickB]

39.99 is gettn too expensive to keep buying bits every week. is there a cheaper alternative to a 1/8 cutting bit for the Carve Tight spendle?
http://www.amazon.com/CarveWright-BCT125P-Cutting-CarveTight-Spindle/dp/B0044BCKK4/ref=sr_1_3?ie=UTF8&qid=1304684866&sr=8-3

[mtylerfl]

im working on a project and was drilling a series of holes 3/4in wide by .563 deep. the holes were not within 3.5in from the end. and i broke 2 bits one right after the other. the 1st bit was a week old, the 2nd bit was brand new. can anyone help me with this issue. 39.99 is gettn too expensive to keep buying bits every week. is there a cheaper alternative to a 1/8 cutting bit for the Carve Tight spendle? I have read some post where someone claims using rotozip bits and strait 1/4 bits, doese anyone have any experience with these. I have not tried other bits yet. I am useing the 1/8 bit to cut holes and to cut thru along a path. but i have not broken one yet during a cut thru on a path.

Hello Capt. Jessie,

Often, it is helpful if we can view your MPC file when troubleshooting problems like this. (However, if any commercial patterns are on it, you should remove them before posting.)

My thought is you can still successfully drill/cut the wood without breaking a bit if you have set your Max. Pass settings shallow enough to take small bites at a time. Did you set a Max. Pass, and if so, what depth dimension did you specify?

EDIT: I see that you already asked what max pass you should set. Sorry I missed that before. On a very hard wood, it is recommended to set the pass at no more than the diameter of the bit (in this case 0.125"), but in extreme cases, it is recommended to set the max pass at HALF the bit diameter (in this case 0.063"). By "recommended", I don't mean CarveWright's recommendation necessarily, rather it's sort of a generic recommendation in the CNC world at large.