BXA Boring tool holder and Dial gauge question

Hi Guys,
Looking for some advice/ideas. When i recently purchased my BXA tool post and holders it came with the "204" Boring bar holder which has a 1inch bore and 3/4 split bushing for the Boring bar. From the quick reaserch I've done it seems an uncommon size boring bar at least locally.
tbh I dont need a boring bar that big. Could I make a new Split Bush say for use with a 16 or 20mm bar. That way I can use my TCMT inserts that I use for my turning holders. If I use a 20mm bar Would I be able to bore the steel 3/4 sleeve to 20mm or is it hardened steel and or better idea to make a new split Sleeve/bushing?

Also looking to purchase a Dial gauge. I already have a couple 0.01mm reading gauges. Is it worth getting a micron(0.001mm) reading one? Are they needed for common lathe and mill work?

Thanks Max:U

Hi Max,

20mm boring bar is still a relatively big bar but I guess it depends on the type of work you intend to do on your lathe. For home machinists I would imagine a 10, 12 or 16mm boring bar to be the most common but once again it depends. The sleeve could well be hardened but you may still be able to machine it out but it may be more trouble than it's worth. It may be just easier to buy a new boring bar but once again it depends on your budget. Don't forget will will need to make a matching tool holder for your inserts. If you are on a tight budget then I can understand you wanting to modify an existing boring tool. Since it's next to useless for you in the current form, you have nothing to loose giving it a go.

0.01mm dial indicators and dial test indicators are the most common gauges used in the home workshop and will be adequate for probably 95% of your work. If you decide you want a 1 micron DI then bare in mind that if you get a cheapie, it may not be any more repeatable than a good quality 0.01mm one!

I just recently bought a 0.002mm brown & sharpe dial test indicator but I bought one second hand since I couldn't justify the prices for a new one and didn't want a cheapie because I figured I'd probably just be disappointed. I have a cheapie digital 0.001mm dial indicator and TBH the last digit is no more than a random number generator! :((

Cheers,

Simon

I faced the same issue with my AXA size boring bar holder, it came with the same to me useless 3/4" split bushing as does the BXA holder. I made two concentric split sleeves for the sizes I uses most, to slide into the existing 3/4" bushing. The two bushings I made are 8mm and 12mm, and can slide into each other.
Attachment 330706Attachment 330707Attachment 330708

he split sleeves have two extra "pseudo" splits, I found it takes less force to clamp. The smaller sleeve is 8mmID and 12mmOD. The larger (brass) sleeve is 3/4"OD and 12mmID. The left pic shows the toolholder with three sleeves nested into each other, and an 8mm boring bar inside.


Attachment 330709
This is a 12mm indexable boring bar in a normal toolholder. I prefer this setup to the clumsy large toolholder above, if the boring bar needs not be rotated as is necesseray when boring small diameters.



Attachment 330710Attachment 330711

For smaller boring tools I use this Ifanger 8mm clamp that fits into a normal toolholder, but lets the boring tool easily be rotated to the optimal angle. It allows a far better view of the job being done, compared to the clumsy boring bar holder with the 3/4" sleeve.

As for the dial gauge question, it depends what you do and how you like to do what you do:D. I would rather buy a 0.01mm DTI, its more useful than a DI. You have no use for a 0.001 DI or DTI right now. You will know when the time comes that you need one.

Many thanks for the reply guys, Another reason i love this forum, even though I can't give much in return as a newbie except a big thank you.

I do have a 12mm boring bar(TCMT) however have used all my tool holders for other cutters so I figured I would use the boring holder as its intended. Looks like I will be turning up a 12mm ID to 1 inch sleeve or 3/4 OD.

Thanks Cba for the pics, looks like you have already done it. I see what you are saying re the big tool holder. Just seems like overkill for a 12mm bar. I may end up getting a 16mm bar just for the extra length that it provides over the 12mm and make a sleeve to suit.
I also hear what you are saying regarding looking inside the bore. Also a smaller bar gives more room for chips coming out.

I dont do any big work needing a 20mm bar at least not at the moment:U

Simon, great point regarding the dial gauge. If I do get one it will be of good quality. At the moment i have a MX 0-10mm Jeweled dial gauge and a Mitutoyo 0-20mm. From my limited experience the MX seems good but you can tell the Mitutoyo is very good just by how it moves, Does that make sense? I also have a Mitutoyo DTI 0-4-0mm
Cba, I see your point re knowing when I will need it. realistically I don't need more precision than 0.01mm.

Many thanks for your input!

some pics of what i have recently made.
I had some 80mm Diameter Titanium bar 6AL-4v ELI that I used as the price was right even thought it required a lot of turning to the right OD.
These nuts are (1 only needed) for the front sprocket of my bike. 27mm hex 20x1.5 thread. I made 2 extra for other people.

Why not just gain some more experience and make a few more tool holders to suit your quick change and the size tooling that you have.

In theory pipeclay that would be a great idea, thank you. I'm thinking(correct me if I'm wrong) the material to make one would probably be similar price or more than buying a toolholder? Also the time spent making one could be time making things that I actually want/need to. Limited time in the garage means to pick and choose my projects as I'm sure anyone with a toddler would understand:U

Probably would work out similar for one off,but as you already are using all your available holders extras would probably fit you priorities for making things you need.

yes indeed I do need more which I can buy except i can't purchase 1 off parts that I make myself. Would i need a surface grinder to make a toolholder and dovetail cutter? I assume the surfaces(tool post side) are passed through a surface grinder and hardened?

I wouldn't think you would need to grind them,I don't grind the ones I make and I don't have any problems,yes a dovetail cutter would be the preferred method in my opinion.

Quite a few can be made with a single cutter.