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Spade Drill - Radial Arm Drill Press?

FullFusion

Plastic
Joined
Apr 5, 2012
Location
Burlington, Ontario, Canada
I have a part that consists of two metal plates 1” thick separated by a hub. The distance between plates is 2.5” and the total distance is 4.5”, the material is mild steel.
I need to drill and ream 6 equally spaced holes to a size of 7/8” diameter.
I would like to do this on my radial arm drill press holding the part in my Hartford SuperSpacer to index the holes.
I would like to drill the holes in one pass to save time, then ream to the final 7/8” diameter.
Is a spade drill a good choice for this? Will the holes align after drilling to allow the reamer to do its job?
Any suggestions for another method.
Thanks
Jim
 

GregSY

Diamond
Joined
Jan 1, 2005
Location
Houston
Why not use a normal twist drill? Sounds like a good fit. Holding it with Super Spacer sounds a little shaky, though.
 

Thunderjet

Hot Rolled
Joined
Jun 24, 2019
Is a spade drill a good choice for this?

No. Twist drill, then ream.



Will the holes align after drilling to allow the reamer to do its job?
Any suggestions for another method.

I doubt it.
I would clamp them together, then drill and ream your first hole, and put a plug in the finished hole to keep the two plates aligned.

Then move on to the next hole and repeat, you could probably plug three holes, then finish the remaining operation.

That's how I would do it anyway.
 

guythatbrews

Cast Iron
Joined
Dec 14, 2017
Location
MO, USA
I agree a spade drill is not the way to go, especially for through holes. They are terrible when they break through, and with a smaller body after you go through the first hole no support for the second. I only use them when I don't have anything else for whatever reason, usually because the hole is great big.

You don't mention any location tolerance. Maybe you don't have a specific location tolerance. If it just has to work then drill and ream will work fine. If it needs to be closer spot drill and drill first layer then spot drill and drill second layer, then ream through.

I always hated using a radial drill becuase of finding location. If we had to do anything close we'd make a drill jig. Ugh!

I guess the holes are on a bolt circle. Don't know how big your part is versus spacer but as long as they are of a size spacer should work fine.

How are you going to locate the first hole to get started?
 

FullFusion

Plastic
Joined
Apr 5, 2012
Location
Burlington, Ontario, Canada
Thank you for all of the replies!
Can I use the 27/32” twist drill without a pre-drill of another size? I will use a centre drill as mentioned above to locate the holes.
The location isn’t so critical, the tolerance is quite open. I will layout the first hole with standard layout tools and centre punch, then rely on the SuperSpacer for the spacing.
I’ve made a jig to hold it in my super spacer, that is working well.
Regards
Jim
 

eKretz

Diamond; Mod Squad
Joined
Mar 27, 2005
Location
Northwest Indiana, USA
A Hartford Super Spacer will handle that no problemo as long as you have the part held rigidly. Those are pretty darn stout. Depending on the rigidity of your radial arm drill, (how far are you extended out on the arm? What size ram?) you might want to double drill, then ream. They can have a tendency to lift as the thrust force on the drill goes up with power feed, causing possible misalignment of a longer hole. Probably won't be a big issue on a very large radial arm, might be on a smaller one.
 

guythatbrews

Cast Iron
Joined
Dec 14, 2017
Location
MO, USA
Thank you for all of the replies!
Can I use the 27/32” twist drill without a pre-drill of another size? I will use a centre drill as mentioned above to locate the holes.
The location isn’t so critical, the tolerance is quite open. I will layout the first hole with standard layout tools and centre punch, then rely on the SuperSpacer for the spacing.
I’ve made a jig to hold it in my super spacer, that is working well.
Regards
Jim

In a radial drill press just use the 27/32, in a drill press step drill unless you've got a big, beefy drill press. Unless the top layer will deflect cause then it will grab the drill. 1" thick doesn't sound like it will.
 

FullFusion

Plastic
Joined
Apr 5, 2012
Location
Burlington, Ontario, Canada
Thank you all for the help.
I’m using an Arboga radial arm drill press with an 8” column and 36” arm. Compared to most of the radial arm drill presses I see it’s on the smaller side.
I will try first with a centre drill and then go direct with the 27/32”. I’ll let you know how it works out next week. I’ll order the drill in on Monday.
Regards
Jim
 

GregSY

Diamond
Joined
Jan 1, 2005
Location
Houston
I, too, assume the part is already welded as the OP says 'part' and not 'pieces'.

Since there are no tolerances on the positioning/alignment of the holes, and it is being done in a drill press, I also assume that the holes will be in perfect alignment after the dust settles.

The 'drill the holes then weld it together with an alignment pin' idea is OK....but after you weld two pieces of 1" steel together....you'll probably have to drive the alignment pin out with a press, if the alignment pin was tight enough to start with to qualify as an alignment pin.
 








 
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