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Installing a DRO on a Hartford Bridgeport Clone.

YYCHM said:
Are you using a fixed speed drill? I've never burnt up a HSS bit drilling CI with a variable speed drill. It's slow going but eventually ends up deep enough.
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I'm using a small 12V milwaukee variable speed drill. It's the only thing small enough to fit in there.

For everyone's info, I'm also using wd40 as a lubricant/coolant.

It's good that you are asking questions like that Craig. I must confess that it feels really really weird to have such a horrible experience. I've been drilling things all my life - including cast iron. But I feel a little bit like a guy who is drilling concrete who doesn't know about hammer drills. There must be something that I don't know about drilling cast iron - but what is it?

Hopefully my carbide bits arrive today. From everything I've heard on here and elsewhere, carbide is the way to go.
 
DPittman said:
Ok I'll be the smart ass....do you have your drill in reverse? LOL

You must have some really hard cast iron but I'm sure a carbide bit will sail through no problem.
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No but it sure feels like it! LMAO!

My fingers are crossed on the carbide. I'm gunna be plenty disappointed if it doesn't come before the weekend. I'd really like to get at least one scale working. Besides, it's a great break from doing taxes.
 
what kind of RPM are you running? too slow and it'll burn up bits in a hurry. For a 1/8" drill the ideal speed in cast iron is 4-5000 rpm. You'd probably be just fine at 1500-2000, but much slower and the bit will suffer. Also, WD40 is not really a cutting lube, although it does work on aluminum to prevent chip welding.
 
Darren said:
what kind of RPM are you running? too slow and it'll burn up bits in a hurry. For a 1/8" drill the ideal speed in cast iron is 4-5000 rpm. You'd probably be just fine at 1500-2000, but much slower and the bit will suffer. Also, WD40 is not really a cutting lube, although it does work on aluminum to prevent chip welding.
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I'm not sure my milwaukee will do anywhere near 5000 rpm. But I have not measured it. I'll try to do that later today.

I wasn't imagining that the wd40 would act like a cutting fluid - only as a coolant. I've always heard that cutting fluids were not required on cast iron because of the carbon. But this may well be a part of my problem.

Your comments about the speed might also be important Darren. I did the math which said that my speed should be 4500 (the middle of your suggested range) so I ran my drill at maximum and burned up a regular drill bit.

I dropped the speed to what felt like half that,..... And burned up a drill bit. I dropped it to a few hundred rpm...... And burned up a drill bit. Tried again with cobalt...... And burned up another bit. Fiddle Fkd with sharpening bits and just burned them up too.

In other words, fast or slow or mid range all burn up bits.

Also tried with various levels of pressure - same results.

I have to go to Windsor today (2 hour drive) but I'll measure the actual drill speed later today sometime.

Edit - I REALLY appreciate your suggestions and comments as well as those of others. I'm not used to total failures like this. I really do feel like I'm missing something simple. I've drilled a crap load of cast iron in the past and never had an experience like this one.
 
I was using a cordless that runs at 2000 RPM and found that not using any lube worked the best for me. Just speculating here, but the slow speed and lubricant/coolant might work against you.
 
Must be some tough stuff in that cast iron! If you burn up a carbide drillbit, i'd suggest mounting the scale with 3m double sided tape or magnets and just forget drilling LOL
 
Darren said:
Must be some tough stuff in that cast iron! If you burn up a carbide drillbit, i'd suggest mounting the scale with 3m double sided tape or magnets and just forget drilling LOL
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Trust me, that tape has crossed my mind....... LOL!

I don't think I have the guts to try magnets with a magnetic scale though......
 
Hacker said:
I was using a cordless that runs at 2000 RPM and found that not using any lube worked the best for me. Just speculating here, but the slow speed and lubricant/coolant might work against you.
Click to expand...

I initially tried no coolant and burned up the drill bit. That's why I switched to a coolant like wd40 (not cutting fluid). But as you have prolly read, nothing has worked.

Not ready to give up just yet.
 
Darren said:
You'd probably be just fine at 1500-2000, but much slower and the bit will suffer.
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Had a few minutes before heading to town and was curious. I measured the cordless drill at 1260 with no load in high speed and 410 at low speed.

So speed might be the issue.

I'm thinking carbide will prolly want even more speed so......
 
"some" of the Carbide bits I ordered arrived today.

1/8 & 11/64 both 113°

Hmmmmm don't know about that angle..... Prolly should not have been so trigger happy when I ordered.

Also, neither one is really the drill bit I needed to tap a 4mm-0.7 or a 5mm-0.8 hole. So now I have two more worries.

1. Is 113° ok for HARD cast iron?

2. Will a #29 HSS Cobalt drill grab in a 1/8" hole in cast iron?
 
Tom O said:
Time will tell… Film at 11:00.
I would think they would work.
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No film at 11. Grandkids have arrived for spring break. Nona would cut off my tools.

By reading the rest of this post, you explicitly agree to my privacy policy which stipulates that nobody can divulge my exact activities when I went out to put my tools away and turn on the alarm. In those brief moments I'm pretty sure I dreamed about trying a little dry peck that seemed to work. It's promising......
 
Susquatch said:
No film at 11. Grandkids have arrived for spring break. Nona would cut off my tools.

By reading the rest of this post, you explicitly agree to my privacy policy which stipulates that nobody can divulge my exact activities when I went out to put my tools away and turn on the alarm. In those brief moments I'm pretty sure I dreamed about trying a little dry peck that seemed to work. It's promising......
Click to expand...
What seemed promising?:rolleyes:
 
JB Weld a 1/4" plate (material of your choice) to the cast? It can be drilled and tapped with holes where you need them, ahead of time and mount the scale Brackets to it. I would think 1/4 would give you enough threads to be secure enough
 
ShawnR said:
JB Weld a 1/4" plate (material of your choice) to the cast? It can be drilled and tapped with holes where you need them, ahead of time and mount the scale Brackets to it.
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This is a great idea that is infinitely better than permanent tape. Let's hope it doesn't come to that.

The carbide drill bits are very promising but have to wait a few days longer. Apparently we have some of the grandkids for a few days and I have been assigned to supervise them. However, they are not old enough to apprentice yet, and the bride doesn't think chaining them to a tractor tire while I work on a DRO is a reasonable way to keep them out of trouble.
 
@Susquatch I didn't quite catch if you are drilling these holes on the a factory machined surface or native casting surfaces? If casting surface, I wonder if this is some skin affected zone where molten CI meets mold. So maybe some embedded silica sand or chilled metal or some such effect that's making it nasty to drill? Now that I think about it, I had one hole that caused me grief, almost like it hit a rock. Maybe a masonry drill would make a better start hole, but either way, might bugger up a perfectly good carbide (machining) drill.

A 'glued on' DRO plate maybe has some merit because you could pre-attach the plates to DRO scale & that could be positioned to irregular casting. The glue thickness makes up the irregularity & molds to the surface. The trick is how to keep it accurately positioned during cure. I would grind the paint (and mystery Bondo) off you so are at native metal. I would also recommend some means to post micro-adjust the scale. Kind of hard to explain but actually actually easy to make - a plate with set screw 'triad' that allows the scale to move in/out or alter its plane once you are fine tuning alignment with a DRO. Newall has an ingenious post that does all this with a single threaded drill hole, but it may not lend itself to your more rectangular scales. (Newall scales are tubes).
 
PeterT said:
I didn't quite catch if you are drilling these holes on the a factory machined surface or native casting surfaces?
Click to expand...

For the X-Axis I'm installing now (the 1st of 4 scales) it's the machined rear side of the table and the machined rear side of the saddle. No virgin castings or paint to deal with (yet). The Y and z axis will both involve some virgin surfaces. But one step at a time.

PeterT said:
A 'glued on' DRO plate maybe has some merit because you could pre-attach the plates to DRO scale & that could be positioned to irregular casting. The glue thickness makes up the irregularity & molds to the surface.
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Yes, if carbide doesn't work I am leaning toward a glue on job. But I won't glue the scale to the mill. I will pre-drill and tap a piece of flat steel to fit the DRO mounting screws and then glue the flat plate to the mill. I don't anticipate any problems doing that.

My scales come with three small levelling screws on each end. They are built into the scale end caps. They will work fine to adjust the scale to the mounting plate or to the mill directly.

But again, I'm hoping that the carbide drill will work. Too bad they arrived so late. Otherwise I'd already know where I am at with this.
 
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