# Carriage Drilling Adapter



## Hawkeye (Mar 31, 2014)

A friend of mine made one of these a few months ago. I thought he meant  something you attach to the carriage so you could drill sideways through  the work held in the headstock. Turns out, it is intended to hold a  chuck or tapered-shank drill bit on the carriage so you can drill  longitudinally into the work spinning on the headstock. Confused yet?

I started with a block of steel 3" x 2 1/2" x 2" and notched it to mount  in the four-way toolpost. Then I drilled and bored it to hold an  R8-to-MT3 adapter I had on hand.


 


 


 

Two comments at this point. First, if you don't have a boring head,  consider getting one. Normally used on a mill, they can be useful on a  lathe. Second, if you are boring into a piece on the carriage, or using  the drilling adapter, you will need a crossfeed lock. If you don't  already have one, add one. It can be as simple as replacing one gib  screw with a setscrew that can easily be tightened and loosened.


 

Once the block was bored to a snug slip fit for the MT3 adapter, it was  drilled and tapped to take two 3/8" SHCSs. Then on to the horizontal  mill to slit in to the bored hole.


 

The drilling adapter is used as shown to hold a tapered-shank bit ...


 

Or a chuck - anything on an MT3 shank, including the boring head.


 

Now, if you're wondering why bother, when I'm drilling a really deep  hole through stock held in the spindle, it takes a lot of cranking to  move the bit in and out of the work to clear chips and add oil. The  crank on the carriage is a lot faster, plus, I can now use power feed  when it's appropriate.


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## Sharky (Mar 31, 2014)

Nice work.  
One question:  Why clamp the taper, the taper should be self-locking like the tailstock?
                    -Just a little extra precaution?


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## Hawkeye (Apr 1, 2014)

Read back a bit. The taper is inside the R8-to-MT3 adapter. The outside of that is parallel. The part I made clamps around the adapter with the two cap screws. The MT3 shanks are, as you say, held only by the taper fit.

I could have done an MT3 bore directly into the block, but I had a perfectly good one already made, so I used it.


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## Sharky (Apr 1, 2014)

Duh.... I guess I missed the R8 part.... 
Still, nicely done, I think I need to swipe that idea,  
Sure would beat moving the tailstock back and forth for deep holes!


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## Hawkeye (Apr 1, 2014)

When I was making my threading dial, I was already wishing I'd made this adapter. And, of course, I stole it from my buddy, who has a commercial machine shop.


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## george wilson (Apr 2, 2014)

Dean Smith and Grace lathes have a drilling adapter built onto the carriage. But,they are exceedingly heavy duty built machines. Even their 13" lathe is very massive. I'd urge being careful to not put excessive pressure on the carriage(which will try to twist it),when using it to power feed drills.

It could also be very hard on your feeding mechanism. I can't say what the maximum drill diameter should be,but for example,maximum drill diameter used on a Bridgeport milling machine on the power down feed is only 3/8". Drilling puts a great deal more strain on the lathe's components than ordinary turning operations. You are cutting TWO very wide chips,and the very center of the drill is not a very effective cutting tool if you look at it and think about it.

Be careful you don't jerk the face out of your quick change gear box,or bugger up the power feed gears. They really rip you for spare parts.


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## itsme_Bernie (Apr 2, 2014)

george wilson said:


> Dean Smith and Grace lathes have a drilling adapter built onto the carriage. But,they are exceedingly heavy duty built machines. Even their 13" lathe is very massive. I'd urge being careful to not put excessive pressure on the carriage(which will try to twist it),when using it to power feed drills.
> 
> It could also be very hard on your feeding mechanism. I can't say what the maximum drill diameter should be,but for example,maximum drill diameter used on a Bridgeport milling machine on the power down feed is only 3/8". Drilling puts a great deal more strain on the lathe's components than ordinary turning operations. You are cutting TWO very wide chips,and the very center of the drill is not a very effective cutting tool if you look at it and think about it.
> 
> Be careful you don't jerk the face out of your quick change gear box,or bugger up the power feed gears. They really rip you for spare parts.



Thanks for the tips George, I hadn't thought of that at all.  Lucky you posted this before I did any more...

Bernie 



Bernie


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## Hawkeye (Apr 2, 2014)

All good points, George. When I said "when it's appropriate", I was already wondering if it would ever be appropriate. Maybe drilling plastic.


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## george wilson (Apr 2, 2014)

I'm not saying it should not be done at all,just urging caution when using the kind of light lathes most hobby guys have. I don't use my Bridgeport clone for power downfeed drilling at all. It seems to be a very nice machine,but being not the real thng,I can't be sure of how rugged the internal parts might be vs. a real Bridgy. I'd hate to have to find parts for it since it was made in 1986. Even newer Asian made machines are often big problems for the makers to identify their OWN products.

You can see the mill beside me on my left in the avatar. That's a Deckel fp1 sticking its head up in the back ground. When I got it,the power feed was not working. I took a chance on it as the guy owed me money(and that was the only way I could see getting it BACK!!).Turned out to just be a sheared off soft steel pin way down in the bottom of the column(which is just FULL of gears). The pin was about 1/8" in diameter,and made to shear off. I have seen 2 lathes with their QC gear box faces jerked off,though. One was jerked off because someone sheared the pin,and replaced it with a STAINLESS STEEL one!! It was a 9" South Bend. The other was back in the 60's and I can't recall the make.

I had a Sharp lathe at work that needed a tailstock part. I could not get the makers to correctly identify their own product. Ended up making the parts myself. And,that is a good Taiwan brand.


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## itsme_Bernie (Apr 2, 2014)

George!

You have a Deckel?!   I saw an MKII Deckel FP1 in person once, and have never gotten over it hah hah.  Just an incredibly well appointed machine, and looked like such a prototyper's machine.  My gosh

Bernie


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## Hawkeye (Apr 3, 2014)

The main thing that makes me hesitant about power feeding a drill is that you can't feel it. Other than subtle changes in sound, you have no hint that something is going wrong until something breaks.


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## george wilson (Apr 3, 2014)

It will help your carriage forces a lot if you drill a smaller hole first,so the flat,chisel end of the larger drill doesn't require as much force to push into the metal. You are exactly right: You can't feel the forces. When I start to drill with this setup,I'd keep an eye on the corner of the carriage to see if it shifts sideways a little bit,trying to twist. Use only very sharp drills and fine as possible feeds. Try feeding the carriage by hand and try to see how hard it is to feed the drill along.

 Actually,you'd be just about as well off hand feeding the carriage,since with a quick motion,you can withdraw the drill anyway,with the carriage hand wheel. I'd use the drilling attachment in that manner,and forget power feeding. What you really wanted anyway was to not have to mess with cranking the tailstock back,and you have it with this attachment.

Don't forget either: The gear that engages the rack is a LITTLE gear. On an Asian machine,it likely is not heat treated. When I had a 12" Atlas,I think I had to replace that little gear,which was no larger than a quarter(25 cents). It was mounted on a 3/8" square teeny shaft,too,IIRC. SO,have mercy on the little gear!!


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## Hawkeye (Apr 3, 2014)

I'm not overly concerned about the strength of the Storebro. It isn't the heaviest lathe ever built, but it certainly isn't a hobby lathe. It has a 50mm diameter post on the compound that expands inside a close-fitting pocket in whatever toolpost you choose to mount. The post expands at the same time the toolpost block is being pulled down on the compound. I've never had the toolpost or the compound angle shift yet.

Having said that, there isn't much chance that I'll be power feeding a drill bit. I have raised the knee of my Victoria under power a couple of times in a drilling operation, but it is dancing around the limits of my comfort zone.


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## hman (Apr 4, 2014)

Last June, I added a tailstock-to-carriage coupling to my 9x20 lathe.  Mounted a simple door hinge to the tailstock, with a pin on the bottom of the moveable hinge leaf.  To drive the tailstock with the carriage, lift the leaf, bring the carriage and tailstock together, and drop the pin into the T-slot of the cross slide.  See photos.  The middle hole in the hinge (and tailstock) provide clearance for the pin, allowing the moveable leaf to hang flat when not in use.

After using the system a couple times, I noted that the pin would sometimes ride up and out of the T-slot.  Solved that by filing away some of the threads on the pin (a #10 screw), leaving the bottom 1/8" or so at full diameter.  This hooks more securely into the T-slot.


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## mcdanlj (May 15, 2022)

george wilson said:


> It will help your carriage forces a lot if you drill a smaller hole first,so the flat,chisel end of the larger drill doesn't require as much force to push into the metal. You are exactly right: You can't feel the forces. When I start to drill with this setup,I'd keep an eye on the corner of the carriage to see if it shifts sideways a little bit,trying to twist. Use only very sharp drills and fine as possible feeds. Try feeding the carriage by hand and try to see how hard it is to feed the drill along.



Thank you! I know it's been eight years, but I'm grateful for having finally found this and understood it.

I just tried carriage drilling, using an #3MT adapter in my QCTB for the same chuck I use in my tailstock. I used the finest feed on my lathe. I drilled 0.1" per pass clearing chips between passes, but thought that power feed would give nice even pressure and improve the quality of the feed. To release the power feed easily and not damage the carriage feed gears, I added momentary slight feed pressure with the handwheel while disengaging the carriage feed; that clearly worked.

I was pilot-drilling almost 5" through with a fresh 3/16" aircraft drill through 1117 CRS, and the hole did wander slightly (maybe .05"? I didn't measure). _I didn't understand why it wandered until reading this quote._

I think I'll keep carriage drilling, but try only feeding by hand to have better feel, at least for pilot drilling.

(Also, I should probably make a spacer to replace my compound for when I don't need the compound, to increase rigidity, if I'm going to do this. I know that a lot of people consider that best practice and it's been on my to-do-someday list for a while.)


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## Hawkeye (May 16, 2022)

It's always good when an old thread like this can help move the process forward for someone. Skilled people like George can add a point of view that makes it all clear.


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