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Home Model Engine Machinist > The Tools and Tips > Machine Modifications > Yet another QCTP thread (BXA on AL320G)

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Old 02-07-2013, 12:08 PM   #1
rodw
 
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Default Yet another QCTP thread (BXA on AL320G)

You guys must get sick of seeing these sort of posts, but here is another one!

Hare & Forbes wanted AUD $500 for a QCTP (I think it is a Dickson Style). The salesman reckons no one bothers to buy it as it is a major job to fit it to the AL320G that has a tool post like this:



I had seen several ways to fit a QCTP to this style of compound, Brian replaced the post (which I did not want to do to a new lathe), There is a two piece sleeve on Youtube, and I worked out yet another way. But in the end I found it was a lot simpler than I thought it might be by following the hollow bolt approach.

The post has a ground 12mm shoulder at the base, thins out to 10.8mm and ends in a M10 thread at the top. The top of the post is well below the top of the QCTP.

I got the BXA tool post from CTC tools in Hong Kong and it arrived in a week from finalising the order. When I looked at it, the post was 15.5mm in diameter and rattled around a bit in a 16mm hole. Off I went to my mates at the bolt shop and got a 16mm mild steel bolt (4.8 grade) with 100 mm of shank above the thread and a nice big high tensile washer. Once again, the blt had a bit of a layer of silt on it from the floods 2 years ago which washed off, but the price is right. While I was there, I spotted a range of extra long drill bits so I grabbed an 8.5mm one.

I had to go out last night but I managed to lop the thread off in the bandsaw, face it to length and drill the 8.5mm hole right through from one end before we had to depart. So far so good. You could actually make this a blind hole but I played safe so that I would not get into trouble with chip buildup making this part. The bolt is 15.8mm in diameter, so it is a lot nicer fit than the BXA's supplied post.



Anyway, after work tonight, I got stuck into it. First ater getting some good advice from this forum, I widened the hole to 29/64" for about 41 mm (plus the drill tip)



Chamfered the edge with a countersink



And reamed it to 12mm which christened my with my super high quality (not) eBay reamer set.



Thanks guys, this worked perfectly!.

The next step was to tap the hole above the reamed section to M10. I knew I would have to sink the tap in as far as it could go and decided to buy a set of M10 taps so I could work up to a bottoming tap to get as many threads as possible without running too many risks.



Initially, I had a bit of trouble holding the chuck and turn the tap until I worked out to stick the toolpost back on and hold the chuck with a lathe tool.



And I kept threading until I ran out room to hold the tap.



That's it guys, Jobs done!



You can see the finish of the bolt is not the best after its dunking in flood waters but no one will know.




This shot shows the detail inside, the 12mm reamed section followed by the M10 threaded section.



I found this a really easy project and it was nice for nothing to go wrong



I found I can finger tighten it right up and finish it off with a spanner so I was happy with my accuracy.

The compound has a nice spring loaded pin that acts as a detent for the original tool post which has four holes at every 90 degrees and I was thinking I would be able to mill these into the base of the BXA. However, this pin caught on the slots for the wedges so I removed it and just squared the post with a set square.

The AL320G is sold as a lathe suited for 12mm (1/2") tooling but has a massive toolpost hat can easily accept 16mm tooling. However, I found that the raised platform on the compound means you can't drop a 16mm tool low enough to be dead on centre. It is about 1mm high on the factory toolpost and the BXA is similar, aybe about 0.7mm too high. I wondered if this had been done deliberately by Hare and Forbes to make you pay another $1k for a lathe that can take 16mm tooling! Maybe if I was Brian, I would just mill the platform off the compound!

I think the BXA is the right size tool post for a lathe of this size. However, if you wanted to use 16mm tools, I think it would be just a matter of milling 1mm off the base of your tool holders. I think I will stick to 12mm tooling.



I did a couple of quick test cuts after aligning two tools to the tailstock and they were bang on first time.

I can't believe how much easier everything has become on my (much) bigger lathe! (And that's before I have used my new QCTP!)


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Old 02-07-2013, 02:43 PM   #2
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Rod, you could always MILL the bottom of the tool post itself

Nice Job!!. Who supplies your Nuts & Bolts? My local Nut & Bolt supplier has gone 'Trade Only' so I need a new supplier.


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Old 02-07-2013, 03:46 PM   #3
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Rod,
Good job! The bolt is refered to as a "Chicago Bolt." Smithy sells them for $3.50 for the AXA holders, albeit, they are much shorter. I've got one! Yours, however is much nicer looking, and should last a whole lot longer.
Dinkin'

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Old 02-07-2013, 05:07 PM   #4
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Originally Posted by trumpy81 View Post
Rod, you could always MILL the bottom of the tool post itself

Nice Job!!. Who supplies your Nuts & Bolts? My local Nut & Bolt supplier has gone 'Trade Only' so I need a new supplier.
Thanks, the tool holder needs to move down further as it is the tool holder itself that limits travel against the compound, so the tool holder needs to be milled to get clearance. The more I think of it, I am sure this lathe is sold as a 16mm machine elsewhere in the world and the compound platform is deliberate to put this its place among a range of tools from Hafco/ Hare and Forbes.

As regards bolts, that is my experience too. I deal with Lightning Bolts at Archerfield. They have gone the same way too. Fortunately, with my body lift kits, I have an account with them and I try to always buy full boxes so they tolerate me when I need to go looking for just one or two. They did me an awesome deal last year on my 200 amp Mig welder. It was too good to pass up even though it was a lot bigger than I wanted it to be. The darn thing weighs 90kg!
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Old 02-07-2013, 05:14 PM   #5
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Originally Posted by toolroom View Post
Rod,
Good job! The bolt is refered to as a "Chicago Bolt." Smithy sells them for $3.50 for the AXA holders, albeit, they are much shorter. I've got one! Yours, however is much nicer looking, and should last a whole lot longer.
Dinkin'
Thanks toolroom, I did not know Smithy sold them, my last machine was a Smithy Midas 1220 and I have ordered parts from them. I did fit a small QCTP to it but all I had to do was make up a sleeve and buy a domed nut to make it look pretty!

I did find one link where somebody had made one like mine and I had thought of the idea as well, I was thinking the weakness of the design was that the column has a gap at the bottom which might not be the best strength wise. This could be fixed with a two part design, but I am very happy with it now it is done and it was certainly the easiest to make.
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Old 02-07-2013, 08:35 PM   #6
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Quote:
Originally Posted by rodw View Post
They did me an awesome deal last year on my 200 amp Mig welder. It was too good to pass up even though it was a lot bigger than I wanted it to be. The darn thing weighs 90kg!
Yeah, I was eying off your Mig earlier, thinking ... how can I distract him ... lol

I have an old DUE Mig that is rusting away in the shed. It needs a new potentiometer and the price of argon mix + bottle is too costly these days, so I haven't bothered fixing it.

I have the TIG welder and the argon for that in a G cylinder is costly enough. When this bottle is empty I intended to buy my own cylinder off eBay.
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Old 02-07-2013, 10:52 PM   #7
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Yeah, I was eying off your Mig earlier, thinking ... how can I distract him ... lol

I have an old DUE Mig that is rusting away in the shed. It needs a new potentiometer and the price of argon mix + bottle is too costly these days, so I haven't bothered fixing it.

I have the TIG welder and the argon for that in a G cylinder is costly enough. When this bottle is empty I intended to buy my own cylinder off eBay.
I know the feeling. I got another handset with a telfon liner, small spool of wire and the feed rollers to do Aluminium but I have baulked at another bottle myself! I've got another project around the house that would see heaps of ally welding but I have no idea if I can do it and it is expensive to find out I can't!
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Old 02-07-2013, 10:54 PM   #8
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Rod - thats a nice job.
I purchased one of these lathes at H&F pre Christmas sale & am very pleased with it. I got an identical QCTP at the same time which worked out cheaper than a CTC tools one which they had on special a month or so ago - postage was the killer.
I machined a 16mm thick piece of cast iron to fit on the cross slide & removed the compound altogether for the time being while I work out how to fit a 4 bolt system - the cheesy two bolt threads have stripped already, but I havent been able to come up with a good mod for this type of compound yet. Any ideas?
Much stiffer without the compound off, so I will probably only put that on when threading, tapering etc.
thanks, & a great mod.
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Old 02-08-2013, 05:38 AM   #9
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Quote:
Originally Posted by lennardhme View Post
Rod - thats a nice job.
I purchased one of these lathes at H&F pre Christmas sale & am very pleased with it. I got an identical QCTP at the same time which worked out cheaper than a CTC tools one which they had on special a month or so ago - postage was the killer.
I machined a 16mm thick piece of cast iron to fit on the cross slide & removed the compound altogether for the time being while I work out how to fit a 4 bolt system - the cheesy two bolt threads have stripped already, but I havent been able to come up with a good mod for this type of compound yet. Any ideas?
Much stiffer without the compound off, so I will probably only put that on when threading, tapering etc.
thanks, & a great mod.
leonard
Leonard, thanks for the compliment. The salesman showed me a totally different toolpost which was recommended for this lathe. I have no idea why as it would have taken a week to fit. It is a shame they did not show me yours, I would have bought it as it would have worked out similar in cost.

I have seen people make new cross slides with some T slots in them (sometimes with a separate area to mount the compound and I am pretty sure people on this forum were talking about a cast iron cross slide blank that is available in the US, not sure if it would fit our lathe. Maybe take a couple of pics and ask a question of the forum.
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Old 02-08-2013, 05:47 AM   #10
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ADDENDUM

Leonard, try these for inspiration
http://www.projectsinmetal.com/forum...for-the-g0602/

http://www.projectsinmetal.com/forum...-when-parting/


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