Hole saws or "Silver and Deming" Bits?

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For drilling larger diameter holes (1/2" to, say, 1.5"), would I be better off with one of those "Silver and Deming" bits, or with hole saws? In my experience, hole saws want to flex and dance around alot, and the teeth can dull fast. I havent ever seen a "Bi-metal" hole-saw that had the small drill in the center for centering the bit, like the wood versions have. Am I doing something wrong? Would I be better or worse off with one the large Silver and Deming bits?Example Silver and Deming bit:http://www.harborfreight.com/cpi/cta...emnumber=43776Are these even made for drilling metal?Sorry for the newb questions  Also, I would be drilling different things from 16gauge pipe to possibly things like 1" thick aluminum bars, etc.*edit*Also, I am building a semi-flood coolant system (more coolant than misting, but not so much that it splashes... maybe a "dribbling" coolant system?) so I hope that helps whatever I do.
Reply:That bit is made like that so that it can be chucked into a 1/2" dril chuck. I've never heard the term "silver and deming" before.That bit would be ok at the right RPM in a drill press. A non-HF bit would be better though, although pricier.I would drill a hole that large in a series, starting with a 1/4" pilot hole, the step up to 1/2", etc... It would take alot of power and a really slow speed to drill a 1-1/2" hole in one shot. Most of us hobby guys have neither. Miller EconotigCutmaster 38Yes ma'am, that IS a screwdriver in my pocket!
Reply:Joe is right.,  It takes alot of horsepower to pull a bit that large.  I personally have never seen a holesaw without a centering bit, but I think a holesaw's limit is 1/4" thick, and even then it needs to be turned slow with plenty of coolant.  How thick of material will you be working with, and how many wholes will you need to drill?  One other thing, if that bit only cost $14 it ain't worth the steel it took to make it.  Good bits that size cost big money.  Remember with a drill bit for the most part you get what you pay for.   ~JacksonI'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:I've been building a tubing bender and have drilled ALOT of 3/4", 7/8" and 1" holes in 1/2" and 5/8" steel using similar looking bits to the one you showed.   I have bought some bits on ebay and some at Tractor Supply.  Slow speed, controlled feed and coolant is key.  Also, as Joe said, stepping up is required.  It's not too hard...just tedious.MM175 MIGCutmaster 38 PlasmaCraftsman 30gal compressor4x6 HF bandsaw1hp HF floor drill pressRyobi Cutoff SawAssorted grindersNot enough time
Reply:I just got done drilling a bunch of holes for the GotTrikes tube bender.  They needed identical holes in 2 pieces of 5/8" thick plate, so I tack welded them together.  I got the Lenox hole saw bits from Lowe's, they worked fine, but they took a long time to get the holes done (1 1/4" thick steel!).  The 1" hole took about 45 minutes to drill, the 7/8" and 3/4" holes took about 30 minutes each.  The first 1/4" goes deceptively fast, the rest will move a little bit, then spin at the same spot for a while, then move a little further, etc..  Go slow, use plenty of cutting oil, and the bits will last, I did 4 each of the 7/8" and 3/4" holes, and the blades still feel sharp.  If you get the Harbor Freight holesaws, they probably won't nearly as long.If I'd known it would take this long, I would have paid to have them done; a friend of a friend has a laser, if I gave him a CAD file, he would cut it cheap.  I've got more 7/8" holes to drill, too, but that's in 2"x2"x1/4" square tube, it won't take nearly as long.  I found out Lowe's sells metal drill bits up to 1/2", then hole saws starting at 3/4", and nothing in between.  I need a 5/8" bit, I'll have to look around.  BTW, cutting oil is kept near the plumbing supplies, nowhere near the drill bits.PatrickLincoln 175HD
Reply:I almost always use hole saws for anything bigger than 3/4" as that seems to be the limit for my drill press using conventional bits.  If you clamp your work piece securely, a hole saw is only limited by its own depth as far as cut.  I have cut holes in 2.5" thick solid on several occasions and the saw made a nice uniform cut.  Hole saws also will last for quite some time if you don't let them chatter and really secure the work well.
Reply:Originally Posted by PatrickJ..BTW, cutting oil is kept near the plumbing supplies, nowhere near the drill bits...
Reply:Make a template and use a torch or grinder for the tubing.  Clean it up with a file.  As stated use lots of coolant.  You will probably need a way to sharpen the large bit or purchase several if this is a project.  Have you thought about a punch or plasma cutter?
Reply:I grew up just blocks where the Silver and Deming bit was invented in Salem Ohio. I worked for the Deming grand daughter and also in one of their old factories after they moved out. S&D never put a patient on the name for their new drills so now days its used for every large dia turned down shank drill no matter who makes it. Unless you have a real slow running drill press i would go with the hole saws...BobSome History http://www.owwm.com/mfgindex/detail.asp?ID=1017Last edited by aametalmaster; 06-21-2007 at 10:21 AM.Bob WrightSalem, Ohio  Birthplace of the Silver & Deming Drillhttp://groups.yahoo.com/group/southbend10k/http://groups.yahoo.com/group/sawking/1999 Miller MM185 w/ Miller 185 Spoolmate spoolgun
Reply:Large bits on thin gage pip can be quite the experience. You'll need a darn good clamping system.
Reply:Starrett bimetal hole saws work quite well. Several other brands as well. They come in depths from lss than 3/4" (for sheet metal... these come in the standard knockout sizes for electrical as well as fractional) to more than 2".On thicker material, peck the hole. This means pull the hole saw out to clear chips regularly. The cut AMAZINGLY fast if the chips are cleared and they are kept cool. It also helps to drill chip breaker/clearing holes around the periphery on thicker material. Drill several 1/4" holes that are tangent to the hole saw path on the inside, so thw saw will intersect them. Attached Images
Reply:Wow, thanks for all the advice! So you guys think I would be better off with hole saws? And better clamps and lots of coolant?By the way I would mostly be doing pipes and stuff, with the occasional thicker bar of aluminum or steel.
Reply:For pipe, just be sure the setup is rigid and don't force the cut. If you are on center, pretty easy. The farther off center, the more rigidity you need, and the more careful you need to be to avoid side-loading the pilot or saw, or distorting the setup. Another (pricey) option, if you have rigid machines, is a rotabroach (or Hougen, or... ) annular cutter. Looks kind of like a hole saw, but actually an annular mill, for higher precision and speed than a hole saw. Not worth the $$$ if you don't need the benefits they give.
Reply:I cut a 6" diameter in 1/4" mild steel with a hole saw, and like everybody else said: good clamps and generous coolant (WD40 in my case).
Reply:To determine what type of cutter, you need to know what type of material, and what kind of machines are available.  I'm not sure the machine and tooling to cut 16 ga, is the same machine and cutter type for thick materials.Having said that... For large holes... Radial drill, hands down my favorite machine. If you've never used one. You should try to check one out sometime. They are not very pretty(usually, not glamorous like having a CNC Mill sitting around the shop) but they sure are great at making big holes. I start with a center drill, then move to something on the order of 1/2" in a drill chuck, then to size preferably with a 4 flute core drill. Because of the size of the "radial arm", these machines can drill to the center of a 6 ft dia round with ease. (some are alot bigger than that) Most have power feed, and flood coolant systems(both a must for large holes)http://www.machinetools.com/MT/machi...27641280207165The best things in life all come on a stick!
Reply:I almost forgot about step-drills. They cost a fortune for a good one, but man they make drilling larger holes easy. I have one that steps up to 1" diameter. I paid like $50 for it , but it's worth every penny. It will drill a 1" hole through 1/4" plate unbelievably fast with no pilot hole. They are also called unibits. Heres a page with a few different bits.http://www.mytoolstore.com/klein/59001.htmlMiller EconotigCutmaster 38Yes ma'am, that IS a screwdriver in my pocket!
Reply:I almost forgot about step-drills. They cost a fortune for a good one, but man they make drilling larger holes easy. I have one that steps up to 1" diameter. I paid like $50 for it , but it's worth every penny.
Reply:According to that link I posted, they're still sky-high. One bit is priced at $76!They are good bits though, and they hold a sharp edge for ages. I've even drilled 1" holes through 1/8"-1/4" steel with a hand drill and a unibit.Miller EconotigCutmaster 38Yes ma'am, that IS a screwdriver in my pocket!
Reply:Thanks guys!I will try to find some Bi-metal hole saws that have centering bits. And I will also look into those stepped drills. For drilling with these, how much pressure should I apply with the drill press?
Reply:I will try to find some Bi-metal hole saws that have centering bits. And I will also look into those stepped drills.
Reply:Make sure you have a way to slow down the speed of the drill and keep it cool.  If the bit heats up it literally anneals the metal in the bit  and makes it softer and the next thing you know it won't cut through a piece of paper.  I run my drill press at around 400 RPMs and at times when doing larger holes it seems to be too fast.  I wish I could get it to slow down even more.Coolant...Coolant...Coolant.   can't say it enough as it will enhance the life of your drills.Michael
Reply:Annular cutters in a mag drill work wonders.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:Ive always found for holes in steel flat bar we will drill them with a high quality twist drill.(up to 38mm) Last week we drilled about 100 32mm (1 1/4")in 12mm (1/2") plate. A 8mm pilot hole and for coolant ordinary cheap engine oil and 300 20mm holes with a 5mm pilot.Holes saws for sure into pipe,Holes sawing into Ally can be unpleasant.
Reply:I should add the quality of your drill press is a determining factor
Reply:Holes sawing into Ally can be unpleasant.Lots of experience on display here and lots of good advice.  Here's my two cents:In my experience, most home drill presses with a single stage step pulley system and a 1725 RPM motor cannot go slow enough for drilling holes above about 1/2" to 3/4."  (That's not a rigorous number - just my recollection.)If you are going to do more than a very few large holes, you might want to consider providing a means of slowing down the drill press.  My very conservative guideline for myself is that if the cutting oil smokes, I'm going too fast for optimum life of a hole saw or drill bit.  That is very conservative and a production engineer would cringe at the lost time, but for my hobby jobs I am more concerned about having those expensive, large bits last a long time than I am at maximizing production.  The big advantage of the smoke test is that it takes no effort to implement and it is always there.  No tables or calculations required.Now, admittedly, I am spoiled on this because I have an electronic VFD (Variable Speed Drive) and I have a Wilton Geared Head Drilling Machine (both purchased at auction or salvage).  But the metallurgical limitations are the same no matter what machines you are equipped with.One option for reducing speed to about 2/3 of your present speed is to buy an 1175 RPM motor for your drill press.  That will only get you a little advantage, but it is something.  I would not hesitate to permanently equip my drill press with an 1175 RPM motor, since I definitely need the lower speed and have never needed the highest speeds.The next option is to fabricate an intermediate pulley arrangement to give a two-stage speed reduction with one stage providing a large, fixed speed reduction.  This can be a little tricky to implement, but, hey, we're welders!The third and, in my opinion, best method of obtaining low speeds is to equip your shop with an electronic VFD and your drill press with a 3-phase motor (required by the VFD).  Welding Web member 383bigblock called my attention to an attractive VFD offering in another thread discussing slowing down drill presses:  http://www.driveswarehouse.com/Drive...00-007NFU.htmlLooks like a good deal at $172 plus the cost of a 3-phase motor.  Don't forget that horsepower requirements are reduced proportional to spindle speed reductions so you will not need high power on your speed reduced drill press.  You can also combine the VFD and the two-stage speed reduction pulley arrangement for torque retention and maximum flexibility.The second thing to be aware of if using a hole saw is the crucial need to withdraw the saw VERY OFTEN (as recommended by enlpck above) to allow chips to clear away or, better, to clean or flush the chips away.  Remember that, once the hole saw has penetrated deeper than the tooth tip-to-gullet distance, the chips have no place to go, unlike for a twist drill which has flutes to provide for chip escape.  The tooth gullets in a hole saw will fill up very quickly and, once that happens, you are no longer cutting freely but are, rather scraping the cuttings around in the annulus generating heat but little action.  (Of course this is an exageration, as some chips will always escape depending upn conditions, but you get the point.)Also remember that that tooth on a large hole saw is traveling a long way in one revolution and generating chips at a rate proportional to saw diameter.  It also is working all the time until withdrawn, unlike the teeth on a bandsaw that get to cool for about 99% of the time.And, of course, use plenty of coolant.awright
Reply:Good advice Awright,Just a couple of points ,     I've always judged my drill speed, feed rate and pressure by the swarf.In mild steel a tinge of gold is fine ,any darker ease off a bit , you will find most oils will smoke at this rate but for commercial applications it is a balance between re sharpening (drill bit), operator fatigue (time) , tool life (including drill).     Another point we drill literally 1000's of holes into 316 1.6mm wall (stainless steel and wire balustrading) I do usually use engine oil again for lube (we have a couple of diesel trucks...plenty of used oil  ) and I have found that the bits last well if at a slightly higher speed than generally recommenced and the bit work better when warmed up through use. The hole sizes I'm talking about are 4.5mm, 6.5mm , 7.0mm 8.5mm and 9.2mm.     Hole sawing into Ally ....yes , when ever possible use a tungsten tipped  hole saw (if that is not available get the apprentice to do it !!!) for lube we use "Alu cut" at 3 % the same as in our non ferrous saws.Oh, and only ever use good quality bits.Better to buy 2 of the size you need than for the same price a kit of 20 bits of a lower quality  18 of which you don't need.Not a bit fan personally of step bits,Not convinced that cobalt or Ti coated bits perform to any justifiable degree better than a good HSS sharpened properly.Last edited by Brett; 06-24-2007 at 04:53 AM.
Reply:I'm putting 1.540 dia. holes in 80" long 4" pipe with a 3/4"wall...Centered about 3" back from the opening both ends..Only "drill" i'm using is a center drill..I use the center drill to make my pilot hole..(all the way thru 5/16")Then I use a 1/2"  2 flute end mill for the next size..Then a 3/4" 6 flute..Then a 1" 6 flute..Then a 1 3/8" 6 flute..Then a 1 1/2" 4 flute..Then to finish a carbide lathe bit in a flytool holder sticking out the last .020..All this is done with a Bridgeport set on the fastest "back gear" speed..Nice finishes and it takes 15 min for me to do 2 holes in each pipe..If you want pics I'll take'em tomorrow.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Wow thanks for all that advice! You have got me wondering now about the use of hole saws vs stepping up with larger drill bits. It seems very plausible that both would take similar abounts of time, since the hole saws would require frequent lifting of the bit. and the larger bits would require frequent size changes. plus now it seems that hole saws and aluminum don't work well together for whatever reason, so I wonder if I should not also try out a few of those large bits also to see how they work (on thicker stuff, at least). Or am I simply missing something? By the way. For the most part, Ill be mostly drilling holes into short pieces of tubing for car parts. However, for other projects I might be needing to drill larger diameter holes in thicker materials. So... what exactly is the problem with hole-sawing Al? Thanks againg for all the help!
Reply:So... what exactly is the problem with hole-sawing Al?
Reply:I'm not a metallurgist, but I think the main problem with hole-sawing aluminum is that most users will not be successful in avoiding too high a tooth velocity and continuing to saw after the teeth are loaded up, resulting in galling and inefficient cutting.If you have an appropriate cutting speed, plenty of coolant optimized for aluminum, and withdraw the saw VERY frequencly, I don't think you will have any difficulty drilling (sawing) aluminum.  It will, however, require patience due to the frequent withdrawal.awright
Reply:I have never had trouble hole-sawing aluminum. I learned early that clearing the chips is key. A coolant spray is real handy here, not so much for th cooling effect, but to wash the chips off the hole saw on each withdrawal. The feed between withdrawals should be a tad less than half of the gullet depth of the teeth. On a hole saw with 10TPI (fairly fine), the gullets will be about 1/12" deep, so the the saw should be pulled about every 1/24" of feed for chip clearing. On a hole saw with 6TPI, pull every 1/16" of feed or more often.There is always the temptation to go a litle more. Don't do it. It will ri the saw and give a crummy hole as well. Note that for this, an air hose with a restricted blowgun is fine for 'cooling', as it will blow the chips out of the teeth and take enough heat from the saw to make it last.