I am using a Dremel cordless multipro 7.2 v. Trying to drill a hole thru a steel mount. It aint easy, takes a loooong time. DO I always use higher rpm??

The motor heats up - do I wait between drills or is it ok to heat up?

How do I know when to change drilll bits, do they ever get blunt?

If there is too much friction /obstruction the motor stops - unless I turn off and ON again. Is this normal?
[Last thing I need now is a broken dremel - atleast that works unlike my plane!!! LOL]

When you remove pieces of balsa from the engine-cowl area , what do I coat it with so as to stain it? Can I leave it alone - wonder what would happen if fuel or oil, grease etc come in contact and will that ruin the wood...?

Thanks
747

747, A dremel is not the tool you want to use for drilling holes in steel. Thin Aluminum may be OK with a small, 1/8" or less drill.

The motor will heat up

When you have to much of a load, it may thermal protect shut off. In this case, it is protecting it's self from buring up

Drill bits will dull with wear, or miss use. Using a Dremel to try to drill steel would classify as miss use. A drill wants to cut between 0.005" and 0.010" per revolution. They should be lubercated when cutting something like steel, or aluminum. Not being able to provide the power needed to get the drill to bite into the stock being drilled will just let the drill spin and heat up, distroying the cutting edge. This sounds like what you are running into. Running it faster only creates more heat. If the drill is not throwing s spiral chip when drilling steel, it isn't cutting properly. You need a drill press, or at least a good power hand drill to do the job.

If you cut into the wood in the engine compartment, it is a good idea to coat the exposed raw wood with a thin coat of epoxy. As you supected, fuel and oil will get into the balsa and soak in. This weakens the wood and eventually causes the glue joints to fail. I always coat the entire engine compartment and holes leading into it whith an epoxy finish. I use Devcon 5 minute epoxy and after mixing it, I thin it with denatured alcohol at a rate of about 25%. IE 1 oz of mixed epoxy would get 1/4 oz of alcohol. This is the hardware store, paint department alcohol, not the drug store varity. I use an acid brush to paint on the mix. Again these are avaiable at the hardware store in the plumbing dept. I use them because they are cheap and with the stiff brissles, I can work the epoxy in to the corners better. I usually throw away the brush after using it. Just remember, the epoxy will still kick off in about five minutes, so work fast.

Don

I have a corded dremel and when drilling metal, i always use about 3/4 of the RPMs. I also use water to cool the bit while drilling. Drill bits WILL lose their sharpness... you may be running a blunt bit.

You should always seal the engine compartment wood. I always use epoxy, but i know you can use wood sealer or I've heard CA will work too. I am sure somebody here has some good advice for that.

No it isnt giving out spiral carvings of steel just powdery stuff! I have already drilled 3 holes. Pls advice what lubrication can I use to drill the final hole with ease! Then I wont break any mounts , and will break something else that isnt replaced with steel!

And for the wood issue , can I use 30 min epoxy mix? So I can work slow...What 's the difference between terms 'epoxy' and 'ca'?
Is it that CA doesnt have to mix? I will get some cheap brushes in HD...

Thanks...I am always learning LOL

to drill steel use heavy feed, low speed and lubricate, lubricate, lubricate. Use cutting oil to keep the hole well lubed. And oh yes, a dremel really isn't meant to drill through steel as you need to bear down on it pretty hard the motor isn't designed for such heavy applications. The dremel instructions in fact tell you not to use pressure but to use the speed of the motor, this is contrary to the requirements of drilling steel. Aluminum you can use higher speed, but if your 100% sure it is steel you are drilling then you need to get an actual drill motor for the job. I can't think of any steel parts needing to be drilled on an RC plane however.

RPM chart here http://members.home.nl/b.ollivier/ht...speedchart.htm

Bottom line you should be drilling at about 1500 rpm in steel with 1/8th drill. Dremels Usually run between 5,000 - 25,000 RPM !!

TOO MANY RPM. Use a conventional home DIY drill **slower is better**. Lubrication while usefull is not required. Spot of oil [any] does no harm.

For your engine bay. Buy a can of fuel proofer see http://www2.towerhobbies.com/cgi-bin...?&I=LXAU33&P=0 Apply two or 3 coats to bare wood. [For small areas I often just smear on some epoxy glue .]

[/quote]
Yes, you can use 30 minute epoxy. In fact, this is a better choice than 5 minute since it gives you more working time and it soaks into the wood better than 5 minute. To thin epoxy, do not mix in solvents such as acetone or alcohol. Instead, just apply a little heat to the epoxy with a heat gun, or a hair drier. Heat works better because it reduces the risk of the epoxy not curing properly. Also, studies have shown that using a solvent causes the epoxy to be somewhat porous when it cures.

CA is cyanoacrylate glue. You'll find it called names such as super glue, instant glue, zap, etc. It's a class of glues that cures very quickly. In a pinch, you could use it to fuel proof, but since the fumes are toxic, I prefer to not use it for large areas.

The other problem with trying to drill steel with high rpms is a process known as "work hardening". The heat at the drill tip causes the structure of the steel to change, resulting in a very hard surface, which just worsens the problem. Ever started drilling a hole in steel only to run into a wall?

As mentioned, the key to cutting steel is a sharp, carbide tipped bit, low rpms, and constant pressure. If your not seeing chips or shavings, your cutting to slow and hardening the metal.

As for lubricants, machine shops have constant flow, typically waterbased lubricants they use to spray at the tip during the process. Typically not practical for your average hobbyist. I've found WD-40 or 3-in-1 oil to be satisfactory, but you must use low RPM to prevent igniting the oil. If you overheat it, you carbonize the oil. The additional carbon against the hot metal just hardens the surface. Keep the work cool, replenish the lubricant frequently, use a sharp bit.

Note that when I say low rpm, I'm talking in the 300-500 rpm range.

Brad

Acetone is epoxy thinner. It is sold as such. Read the label on the next can you see. Alcohol was not created as an epoxy thinner, nor is it the recommended thinner for epoxy. Acetone is.

Acetone is epoxy thinner and while it affects the cure time, the epoxy does cure properly.

Studies have shown that water and alcohol not only cause porosity, but some is trapped within the curing resin and weaken the result measurably. Drug store rubbing alcohol contains water. It's the worst "thinner" you could choose for epoxy.

Acetone was not created as an epoxy thinner either.
It doesn't always cure properly. Also, how handy is it to keep acetone on hand, at $5-6 per quart, for the infrequent occasions that one would use it?
Studies have shown that adding ANY thinner to epoxy causes porosity and weakens the epoxy. Here's an example directly from West Systems, a well known maker of epoxy:


There are epoxy-based products specifically designed to penetrate and reinforce rotted wood. These products, basically an epoxy thinned with solvents, do a good job of penetrating wood. But the solvents compromise the strength and moisture barrier properties of the epoxy. WEST SYSTEM epoxy can be thinned with solvents for greater penetration, but not without the same compromises in strength and moisture resistance. Acetone, toluene or MEK have been used to thin WEST SYSTEM epoxy and duplicate these penetrating epoxies with about the same effectiveness. If you chose to thin the epoxy, keep in mind that the strength and moisture protection of the epoxy are lost in proportion to the amount of solvent added.

There is a better solution to get good penetration without losing strength or moisture resistance. We recommend moderate heating of the repair area and the epoxy with a heat gun or heat lamp. The epoxy will have a lower viscosity and penetrate more deeply when it is warmed and contacts the warmed wood cavities and pores. Although the working life of the epoxy will be considerable shortened, slower hardeners (206, 207, 209) will have a longer working life and should penetrate more than 205 Hardener before they begin to gel. When the epoxy cures it will retain all of its strength and effectiveness as a moisture barrier, which we feel more than offsets any advantages gained by adding solvents to the epoxy.


If that's not enough information, here's more:
In the R/C hobby, we use epoxy for strength, as a chemical barrier, or both. Since thinners compromise epoxy's ability to perform either role, after reading this, and the studies they did to come to the above conclusion, for me it was a no-brainer to stop thinning epoxy with solvents.

Piper-chuck, excellent advice. I have seen many botched repair jobs where people used either alcohol or something else to thin epoxy, a very poor way to do it. Now I do keep acetone on hand as it makes a good cleaner for equipment I used to spread epoxy. It also makes a good solution to store CA caps in when not on the bottle as it keeps them clean.

I think the take away is the above statement from Piper_Chuck. I will keep this in mind.

Also,

What do you guys use to mix epoxy on, as the container becomes like an old lava field after it hardens? Also which is a better way to remove hardened CA, glue, epoxies etc once they are in any object? Do u use drug store alcohol or acetone? Or does this depend on WHERE the stuff has to be removed?

Thanks...And this seems like a useful thread for all!!

--747

And where do I get brushes for cheap, to be used just one time?

http://www2.towerhobbies.com/cgi-bin...&I=LXE269&P=ML
This is the type of brush to use. They can be found at Tower, the LHS, Home Depot, Lowes or many other hardware stores and other stores.

Bristles can be cut shorter to add stiffness if desired.

Rather than retyping the entire thing here, read through [link=http://www.rcuniverse.com/forum/m_6087395/tm.htm]this thread[/link] and choose the method you like best.
Acetone is good for removing hardened CA, but you have to be careful because it will react with certain types of plastic. A common example is that it can cause a haze on the clear plastic used for canopies.

I'm not sure there's anything that will safely remove hardened epoxy. About the only thing I've seen that works is to soften it with heat and then gently pry it off. A better solution is to have alcohol and paper towels ready when using the epoxy and to clean very thoroughly before it hardens. I've found that the drugstore variety alcohol works fine for cleaning off uncured epoxy. An interesting tip I picked up when I assembled a Tower Hobbies ARF is to cut the paper towels in quarters before you start gluing. This way you use less of them.

the only time I have felt compelled to thin epoxy is when I have coated the fuel tank area.
denatured alcohol works well for the clean up of exess epoxy when glueeing wings etc.at about 10$ a gallon it will last forever

I use the cheap children's artist brushes that come with watercolors. They have plastic handles, and plastic bristles. I got 500 of them for $3.99 at Hobby lobby in the childrens craft area.

Thanks for the fuel proof info.
Going back to my Dremel/steel drilling issue. I dont want to invest anymore on any stuff.

I have 4 more oblong holes to drill to fit the wooden mount with the new steel mounts. Is there a way to use my dremel in low speed with any type of new drill bit (carbide? diamond?) and lubricants and get the job done . I can even do it real slowly everyday?

Is this do able with what I have? Pls advise!
thanks
--747

[link=http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&langId=-1&catalogId=10053&productId=100386007&N=10000003+9 0401&marketID=401&locStoreNum=8125]drill[/link]
[link=http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&langId=-1&catalogId=10053&productId=100092815&N=10000003+9 0401&marketID=401&locStoreNum=8125&D=carbide+drill +bits]carbide bits[/link]

Drill seems cheaper than carbide bits. but if you want to keep trying go for it. you highlighted the problem your self with trying to drill through steel with a dremel.

I do fullsize aircraft structural fabrication for a living. slow speed/heavy feed is the rule for steel. lube helps a lot too. a dewalt drill or any good hand drill should do ya fine. dremel runs too fast. work hardening what you are trying to drill is a sure way to kill drill bits and upset you in the process. you don't really need a drill press unless you are drilling thick stuff or large holes. it does help with making your holes perpendicular to your work though or if you are doing lots of holes.

my advice of low speed/heavy feed and lube. comes from USAF experience in structural repair.
Wonder if theres a theme here.

I bet if you look at your local home improvement stor you could find a Variable speed reversing drill for less than 20 bucks. Might not be the best one available, but it sounds like you won't be using it very often anyway. And you may be surprised what other uses you find for it once you have it.

hey another sheetmental troop. how ya doing. I'm @ pope right now. working on C-130's and A-10's. I think that low speed/heavy feed thing is a rhyme they tought us back in tech school. I still have to tell the new kids why they keep smoking drill bits and can't seem to get one hole through their work sometimes. you always know the sound of the drill just spinning at top speed and the look of frustration that goes with that work hardened stainless! they learn it pretty quick.

Happens a lot when newbies try to drill out stripped screw heads. Usually get about 1/16" before full stop sets in. They also don't break screws loose first before hitting them with their high-speed automatic screw stripping guns. Always in such a hurry to get done that they make it take longer in the long run.[:@] Then they cry for help.

Worked on some KC-10's about 20 years ago. Hated those screws Douglas used.

spent 4 yrs at Minot ND. then got out cause I thought (mistake one) that I could do better in the civilian world. Now I'm very seriously thinking about the USAFR while they'll still take me. What would you think about a 38 year old E 4 three level. [&o] But I do miss it.