Thread: Cross-slide play

Thanks Metmachmad,
I was wondering about clearance angle. Am I right in assuming these bars are normally used for boring out largish holes (e.g. cylinders)? They might not be suited to small holes. I can't see what difference it makes whether the boring bar rotates in a boring head or the workpiece rotates in a chuck though.

I'll have a look at the clearance angle today. If necessary I'll grind away some of the bar.

Chris

Originally Posted by Metmachmad

I think those boring bars are more suited to use in boring heads as used in a verticle mill, where the boring bar itself rotates. If this is the case, then your clearance and rake angles might be wrong.

Yes I agree .Those bars work OK for me in the boring head in the DM 45 mill drill . I don't think the rake is suited to lathe work, I don't know why .

I haven't tried machining Delrin yet, I think you need a sharp honed edge for that ? Which Carbide doesnt have. Mike

Clearance angle was the culprit- there was almost none. I ground some clearance on the tool and it worked pretty well. As stated by a few people on this thread, these tools need sharpening. My poor white oxide wheel struggled with the carbide. I'll get some green wheels for the grinder and have another crack at sharpening.

I think these boring bars will do a pretty good job once they are ground to the proper shape. However, if I had my time again I'd just buy a bar that takes carbide inserts.

I also tightened the rearmost gib screw and there is now no sideways movement in the cross slide.

Thanks to everyone for the help.

Chris

Hi Chris,
Good to hear you have it pretty well sorted, and I did warn you about those bars, LOL
I thought you bought them to cut aluminium?

I also don't see any difference between the work rotating or the bar rotating, they both need clearance angles. As for clearance angles that will depend on the size of the hole your doing either way.

The other boring bars would have worked better with Delrin. In the link below you can see the finish I got from carbide inserts used on it.
https://www.woodworkforums.com/f65/an...s-mill-126490/

Dave

Yeah, you did warn me Dave. I did buy them to bore aluminium and hopefully they will do a better job on that. I just happened to have a couple of 50mm long pieces of 50mm round Delrin in the offcuts bin.

Nice job on the Nylon. I will buy one of those carbide insert boring bars and some aluminium cutting inserts. They look nice and sharp and should also do a good job on plastics.

Chris

Hi,
I said it was Nylon in the post, but I think it was Delrin, it just a piece I had as scrap from another job.

Those inserts are not that sharp, the turning tool is one out of the 7-9 piece sets you buy, that everyone complains about being brittle and not being able to buy quality inserts for them. I agree with them all, buy they do still work.

The boring bar as can be seen is Sandvic and the tips are some I got off Retromilling and are designed for steel I am pretty sure. I have the packet and can look if you want to know what they are.

The set I bought is like this one below
16MM (5/8") -9Pce Indexable Tip Metal Lathe Tool Set (Free Postage) | eBay

And they have them down to around 10 or 8mm

12mm (1/2") -9Pce Indexable Tip Metal Lathe Tool Set (Free Postage) | eBay
But like I said above they are brittle inserts and standard inserts wont fit.

Dave

I will probably just get this boring bar in the 10mm size. Then I know it will take standard inserts:

SCLCR/L INDEXABLE BORING BAR #I33

I already have a carbide insert tool holder for turning and facing, so I don't really need a full set.

Originally Posted by jack620

Thanks Metmachmad,
I was wondering about clearance angle. Am I right in assuming these bars are normally used for boring out largish holes (e.g. cylinders)? They might not be suited to small holes. I can't see what difference it makes whether the boring bar rotates in a boring head or the workpiece rotates in a chuck though.

I'll have a look at the clearance angle today. If necessary I'll grind away some of the bar.

Chris

Yeah Chris, I got one of those bars in a mixed lot of tooling I bought. Later I tried to bore a 1.25" hole in mild steel on the lathe with it and it was hopeless. I had to regrind the carbide tip to get it to perform OK.

I thought the same as you,- with everything else being the same, what's the big difference between the work revolving or the tool revolving?, I don' know but somehow it seems to

Any how it seems that you are sorted out and back on track.