Advice for drilling metal

[Brian Kent]

I probably have to drill 4 holes, 5/8" diameter, through the steel base of an engine hoist. (Harborfreight - mis-matched holes).

I have the drill press but not the bit or the experience. What kind of drill bit do I need? I assume I need to use drilling oil. It is better if I can find something at a Home Depot or Toolmart rather than waiting for an online order to come.

Thank you

[Greg R Bradley]

You say "mis-matched holes". Does that mean they partially line up?

If you have to drill new holes, I would use a decent drill bit like a Triumph or Norsman premium bit such as: http://www.harryepstein.com/index.ph...drill-bit.html

That will be $17.85 + freight and you can probably get a few extra killer deals with the order but it will be 4-5 days to get it. You could get the same bit from Amazon in a couple days at TRIPLE the price.

You could do 4 holes with the Dewalt garbage you would get at HD but you will need to use cutting oil and go much slower. Does your drill press do 250rpm?

If they partially line up, I would use a CAR reamer but that will be a lot more money: https://www.amazon.com/KnKut-KK8-5-8...rds=car+reamer

If they mostly line up, I would just use a burr grinder or a good round file to make them line up. The problem with files is that all the stuff at stores is pure garbage. I buy USA made 20 year old Simonds Files from a secret source.

[Brian Kent]

The first picture is when I align 1 hole and draw the other with a marker. Assuming I align the arm correctly on the base, each hole overlaps by 1/2 of a hole. And yes, I can get a very slow speed on the drill press.

[Eric Schmid]

Any twist bit will probably get the job done, but a high quality bit would be best. Both brands that Glenn suggested are good, but I doubt you'll find either at a home center. If you have a good hardware store they might have some good quality bits. If you are using a drill press you can probably just get a 5/8" bit (or two) and have at it. If you need to do these with a handheld drill I would drill a pilot hole first; 1/4" or so. Slow rotation speed and lots of pressure once the bore is started. Cutting fluid will help keep the bit cool and lubricated.

[Bruce Page]

Why not take it back and exchange it? It looks like you're going to end up with a figure 8 shaped hole which will be difficult to drill because the bit will want to grab. One option is to drill with the biggest bit you have (1/2"?) and open it up to 5/8 using a Dremal.
Personally, I would return it.

[Greg R Bradley]

A Dewalt S&D 5/8" bit from HD will probably survive 4 holes for what you are doing and will be less than $20. If it doesn't, their replacement policy will be your friend. You will need to run the slowest speed possible, certainly no more than 300rpm. You will need to have both pieces of metal there so the top one becomes the guide for the lower. I assume you have an inner square tube and an outer square tube and the holes don't line up, right?
The parts will need to be solidly mounted to the table. Drill press vice into tee slots or several metal clamps. It will try to bind so will need to be solidly mounted. Also will need a good chuck tightened well. Hopefully three flats on the drill bit shaft.
When in doubt, a file is much safer. Good ones aren't very slow at all but they are almost unavailable at this point. The best from HD, warrantied when you are done isn't a bad choice. With the soft mild steel from Harbor Freight and only four holes, it might not be that bad.

Edited to add: Since my brother Glenn has 100 times my posts, I guess I will always get called "Glenn".

OK, now that we have pictures, I don't see how you are going to use the top holes to guide you for the bottom holes. I think the file is in order.

[pat warner]

Maybe drilling through 3/16" cold rolled?
Surely will be an interrupted cut = chatter city.
Looks like work holding may be a problem too?
I'd lock up the work on the drill press; it cannot move.
Then find the desired center on the work.
Then clamp some 3/8 aluminum down on top of the work.
I'd get a 5/8" counterbore with a 1/4 pilot.
Drill the 1/4 hole, move nothing.
Then drive the counterbore, flooding the hole as you go.
HSS will work, no need for carbide, speed critical however.
You have to match the feed & speed to the CB cutting rate.

[Brian Kent]

Thank you. And yes, I will first try to return and exchange. The drilling is in case the next one is no better.

[Lee Schierer]

Drilling a 5/8 hole into steel without a pilot hole is asking for problems. Pilot holes will keep your bit from wandering and will make the drilling easier with less likely hood of grabbing. Use a center punch and mark the center of the intended hole and then drill an 1/8" hole. Step up to 1/4 then 3/8 then 1/2 and finally drill to 5/8. It sounds like a lot of work, but the end result will be better. Make sure you clamp the piece being drilled down securely so it cannot move if the drill bit catches. Tapping oil can help cool your drill bits. Use a slow speed and keep your hands clear of the piece at all times.

[Brian Kent]

I took the misfit parts back tonight after work. Harbor Freight was open later than I expected. They gave me a second set of everything. I will set it up tomorrow and bring back the extra parts. Very glad I will not have to drill the holes. Thank you all for your help. I'll let you know how it goes.

[Gene Takae]

I find that even when using a drill press it's difficult drilling a new hole next to an existing one. In that case I find that using a piece with the hole drilled in it as a guide works best. Make it big enough so you can clap it into position.

[Greg R Bradley]

I think you have solved your problem by getting a better set of parts, however, some might be helped by the information that the better metal drills like the Triumph and Norseman Super Premium DON'T require the center punch, pilot hole, and step up in sizes mentioned above. Cobalt may resist heating better, and the cheap HSS can't manage it, the stuff from the BORG is garbage, BUT these good drills have a very narrow web, making them NOT walk and drill quickly and easily. i recently had to drill a number of holes is structural steel over my head - 33/64" which has clearance for 1/2" bolts. I drilled 67 holes with a Milwaukee D Handle drill in one shot without center punch or pilot hole without issue.

The starting web on a 1/2"+ Norseman Super Premium bit is smaller than that on the 1/4" best garbage from the BORG. Just think about an old guy easily drilling 1/2"+ holes over my head in structural steel and you will get the idea of how good these drills are.

Titanium, etc. are just coatings for friction resistance. Cobalt is great for solid surfaces, automated production equipment, and other places where heat is a factor but the Super Premium bits are fabulous for hand use and are just amazing in Stainless and heat hardening steels as you are drilling below the part that is work hardening.

[Michael Zerance]

I use a step bit (unibit) for drilling steel beams, steel plate, electrical boxes for connectors, holes for grommets, etc. It works great and has the added benefit of reaming the burr off both sides of the hole by using the edge of the next size "step" to just touch the surface. No pilot holes, center punch, or expensive sets of bits. I've had it for about 15 years and it still works well, although the point is getting a little dull but once started the steps still cut like new.

https://www.amazon.com/Irwin-Tools-1...ds=unibit&th=1

[Jason White]

Steel or cobalt multipurpose drill bit and some 3-in-1 oil will git 'er done. Go slowly.

I probably have to drill 4 holes, 5/8" diameter, through the steel base of an engine hoist. (Harborfreight - mis-matched holes).

I have the drill press but not the bit or the experience. What kind of drill bit do I need? I assume I need to use drilling oil. It is better if I can find something at a Home Depot or Toolmart rather than waiting for an online order to come.

Thank you

[Jim Finn]

I am a retired sheet metal worker and I like What Eric said...."Slow rotation speed and lots of pressure once the bore is started. Cutting fluid will help keep the bit cool and lubricated."