I Need My Plan Reviewed. I Don't Want To Harm My Lathe.

[jbmauser]

I have a SB9x 48 C and I want to rig a end mill up to cut a bottom plate for the Shars AXA tool post I just bought. My plan is to place a cheap cross slide on the bed of the lathe and have the cross slide supported on the bed not the ways by setting it on some large cutting tools and then clamping it down using long bolts to the bottom of the bed with a cross plate. Since I will not have any thing on the ways I figure that should be OK but I am not sure the lateral torque when cutting will not send the cross slide off the cutting tools. I figure this is a hair brain plan but that is what I can do well. The cross slide is just sitting on the cutting tools in the pics, not bolted down. I just don't want to harm the lathe. Pics attached comments desired. Thanks

 

[12bolts]

Just put some brown paper between the tools and the base of the cross slide. Torque your securing bolts nice and tight and you should be good to go.
If you can you locate 1 of the securing bolts in a position so that it is resisting the lateral force that would be a plus. Also make sure everything is nice and clean of fluids before you start. And debris, any small hard particles against the tools steel may cause them to snap when you lock it all down.

cheers Phil

 

[Tozguy]

Securing the cross slide to the bed of the lathe is the first concern and chances are your idea can be made to work. But if you are cutting the plate to make a T nut to fit the compound, the challenge with that set up would be getting both sides cut to the same dimensions. The T nut must be cut square and symmetric to work properly. Other than the clearances in the dovetail of the cross slide, there is the rigidity of the vise to wonder about.

 

[jocat54]

Chuck it up in lathe and turn the shoulder round. Doesn't need to a rectangle or square--just needs the same dimensions.

 

[jbmauser]

Turning it round makes great sense. I could then grind flats on two sides to bring it down to slide into the saddle. If you all will indulge me a bit more. I looked at the key that holds the candle stick style tool holder into the saddle. It is not a large hunk of steel and it has a large hole in it to allow the tool post to slide in and sit on a small ledge which is machined in it's base. I look at the base of the AXA and consider that it would be much easier to turn that same profile in the plate and use the original "Key". But I look at the sheer mass of the AXA compared to the candle stick style and think that the small original "Key" would not be appropriate. But then I think ... All of the force should be the same on the "Key" no mater which tool post was being held in place. I could even turn a washer /spacer to support the AXA bolt where it will span the distance from the Key to the base of the AXA block.

I guess you all can see that I do not have much knowledge or sense about how the mass of the tooling and the lathe work together to disrupt the metal of the stock and produce chips. Basic stuff I guess but I look at the big hunk of metal the AXA came with and the small amount of metal that supports the candle stick style tool holder I feel I need to talk to people who have a clue so to speak.

 

[Tony Wells]

I'd just go with the turned solution. Much less trouble, and a guaranty that the load bearing surfaces are coplanar, which is important. There was a thread on it, or perhaps a PotD entry....you should look at it before proceeding.

 

[Tozguy]

JB if the 'key' you are referring to is the original T nut from a lantern tool post then I would say yes it can be used for the new QCTP. But if the new QCTP through bolt fits in the old T nut then you are very lucky. Chances are however that you will have to make up a custom through bolt for that option to work. You shouldn't fill the space between T nut and base of QCTP with a spacer.
The blank that comes with the QCTP is beefy so that it can be cut down to fit just about any lathe.

 

[jbmauser]

Yes the Original T nut is from the Lantern tool post. the shoulder at the base of the lantern tool post that is captured by the T nut is 1/2 the thickness of the T nut and mates in a recess in the T nut. I was thinking of turning that dia. and then the through hole dia. to equal the Lantern tool post. The spacer I was thinking of was a bushing so to speak to fill the space beneath the QCTP where the tool post bolt would be unsupported as it is smaller in Dia. then the Lantern tool post. it would not offer any vertical support just side to side in the saddle.

 

[Falcody]

Eagledustoff37@gmail.com builds t-nuts. I had him make one for my 11" Logan. (I don't have a mill yet). He built mine, threaded it, and hardened it to 40 Rockwell for $25. I know that this may not be his price forever, but he did a great job! If you email him put my name "Cody" and the word "t-nut" in the subject line.

 

[jbmauser]

Well, thank all of you for your suggestions and info. I tried to turn it with limited success. This metal plate was hard, very hard. when the cut ran out to the area where the tool was cutting air briefly, the stock took the edge right off the tool. A friend was visiting and he took a grinder to the T plate and whacked off the sides and we ground and filed the thickness down to slide into the saddle. It took some time but we were successful. I am a woodturner and cutting air is common in odd shaped stock. I will have to learn if tool design is a key component to cutting air with metal of if it is not recommended at all.