Needs Pictures: 0
Picture(s) thanks: 0
Results 1 to 10 of 10
-
7th Jul 2018, 11:08 AM #1Senior Member
- Join Date
- Jan 2016
- Location
- Gosford
- Age
- 63
- Posts
- 173
Material selection, (tooling and cutting speeds).
So much to consider. In beginning to turn a replacement feed screw, I was soon reintroduced to an old friend, Parting tool chatter. I ditched that idea of cutting a depth groove and just did it a different way. I'll now require a left and right hand sharp pointed acute angle tool to get the square shoulders I need but that's OK. Last night and this morning, I've been reading up on tool shape, material, cutting speed, feed rates etc. Of course there is the Carbide insert tooling now that I've never really been involved with. HSS is all I ever used or needed to use. I went back to my old College text and it basically just said to double the cut speed of HSS to get the speed for Carbide, but I don't think they knew much about it when they wrote the book and a lot has changed since then. The carbide speeds I'm reading about today are more like 4 - 6 X the speeds of HSS tooling.
I doubt that my little lathe has the spindle speed or HP to make good use of carbide but I will give it a try at some point as it is available for mini-lathes.
So anyway, the Black Bar (yes, I know) that I bought yesterday machines like a pork sausage might. It reminds me of my only attempt to use a pottery wheel. I'm going about it all very slowly in order to achieve anything that might be usable and once I have that better fit with this one (I hope), I'd like to machine another using a more friendly piece of bar. What grade of steel would the experience and knowledge base of the forum suggest I use for a cross-feed screw? I started with a piece of 16mm black but it can come out of 1/2" bar (possibly 12mm) with way less material to remove.
-
7th Jul 2018, 11:22 AM #2Member: Blue and white apron brigade
- Join Date
- Feb 2006
- Location
- Perth
- Posts
- 7,182
Most of my parting and slot problems disappeared when I use one of these parting tools.
https://www.eccentricengineering.com...d=31&Itemid=45
Mostly I use it in the conventional way where it works almost as well as the upside down mode.
-
7th Jul 2018, 01:29 PM #3Senior Member
- Join Date
- Jan 2016
- Location
- Gosford
- Age
- 63
- Posts
- 173
I saw the T profile blades reviewed and tested on YouTube last night. They look the goods but I'm not interested in inverted rear posts. I'm working on a different tool post for the lathe but the low centre height is a problem. There is a little one on eBay but it has no dimensions. The seller is investigating for me.
The 100 series doesn't fit which is a shame since I can get a really good deal close to home. A 4 way piston action with 11 tool holders (duplicates obviously) for $225. Ex-importer wanting to clear stock.
I re-ground the tool I have and it did the job this morning in new light. Old eyes make hard work and I'm not really that old yet.
-
7th Jul 2018, 03:42 PM #4Most Valued Member
- Join Date
- Aug 2011
- Location
- Melbourne
- Posts
- 4,779
Boy I have had some hair raising moments when parting but with care and patience, most of the issues relating to parting off can be sorted out. I still get nervous when parting eventhough I don't have issues anymore, it's because I have bad memories from a time when I was just starting out.
WRT leadscrew material for the cross slide, Duraflex 1045 or for something even tougher then 4140. I guess it depends on when you, your tooling and your lathe can handle. 4140 is pretty tough but not impossible. Duraflex is nice stuff to machine and it can be hardened after machining if you wanted to go that far.
SimonGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
-
7th Jul 2018, 06:01 PM #5
Hi Glivo, Guys,
I would just stick to HSS for now, I have a Myford S7 which has a much higher top speed but not the power to take advantage of carbide tooling, though I do admit to using carbide threading inserts quite successfully. Some materials are really difficult to get good finishes on. For these I use a "Shear" tool. This can take very very fine cuts and is useful for getting tight dimensions, such as bearing fits.
Re Parting: I made and use a rear toolpost with the blade inverted ! Since I did this I've had no problems at all and can even part some materials under power, though I prefer not to.
As far as the cross screw is concerned, you can purchase suitable threaded rod and matching nuts if you wanted.
Watching your progress with interestBest Regards:
Baron J.
-
7th Jul 2018, 07:27 PM #6Senior Member
- Join Date
- Jan 2016
- Location
- Gosford
- Age
- 63
- Posts
- 173
I'll post specifically about the lathe parts on that thread. Thanks for your input here though BaronJ. The parting issue I had was, as I expected, down to tool shape and bluntness. I just used a tool that came with the lathe. I was able to rind it up and get a good result. You've confirmed my thoughts about the Carbide though. My reading has indicated that you need speed and power. The Advance has neither. Although a bigger motor and some changed pulleys wouldn't be difficult, its not a certainty that the bearings would fair too well. It already drinks oil like I drink beer. Well almost.
SimonL. If I can turn a plain steel black bar machined to the fit, on the lathe that requires the part, I'll investigate other material for a second go later (and I think that it will be an achievement in itself with the catch 22 factor). BaronJ's suggestion of threaded bar is something I'd already considered but it will involve some fabrication as it is a single machined part that I'm replacing.
-
7th Jul 2018, 07:34 PM #7Most Valued Member
- Join Date
- Apr 2012
- Location
- Healesville
- Posts
- 2,129
If you are using the advance lathe to make the screw then 1020 would be my choice, you should get a good finish and although it is not a hard steel if it is oiled regularly it will last a long time. Do you have a traveling steady?
good luck, shed
-
7th Jul 2018, 08:13 PM #8Senior Member
- Join Date
- Jan 2016
- Location
- Gosford
- Age
- 63
- Posts
- 173
Thanks for that shed. Unfortunately, no steady, and I'm already thinking it may be a necessity. If not for this job then certainly for others. 4" (3 1/2" required thread length) at 3/8" diameter might get a bit flexy in the middle, although so far so good. I'm only doing very light multiple cuts of 0.2mm at a time to start with and then down to 0.1mm for a couple to clean up and using lots of cutting oil. Indexing the thread to the lead screw is easy so far without a dial indicator. The dial indicator I put on the cross-feed is working out really well.
-
7th Jul 2018, 11:54 PM #9
cross feed
I bought the new threaded rod for the cross feed on the Sheraton 9 lathe ( a US seller can't remember who ) . I did what most others do and turned the end of the new rod down and then cut off the end of the old worn cross feed rod, bored a hole into it and pressed the two bits together . Also did this on a CVA mill cross feed ( made the new ACME thread rod from 12L14 ) . On the CVA I also made a new Delrin nut, I tried the heating/melting method, it's rather tricky but after a few goes it came good - using this method , the nut is an almost perfect fit on the new threaded rod .
-
8th Jul 2018, 02:19 AM #10
Hi Morrisman, Guys,
I made a digital hight gauge adjusting nut using the heating/melting method, I used a length of well greased M6 threaded rod and about 1 1/4" length of black Acetal (Delrin) rod 20 mm diameter cut lengthwise in half. Heated the threaded rod with a blowlamp until the Acetal stuck to it, and then clamped it in a vise so that it was crushed around the threaded rod, continually heating the rod at either side of the acetal so that as it melted both halves became welded together. I then ran cold water over the whole lot to cool it down as quickly as I could.
Removing the now cold plastic nut was quite difficult simply because it was quite long in relation to thread diameter, but its tightness made it very easy to turn the outside down to make it concentric and a good press fit in the holder. There is absolutely no measurable play or backlash in the nut. In fact I had to run the threaded rod up and down the nut a few times to ease it off a little.
I've since made several nuts in this way, one of them for an X-Y table cross feed. Not that there was anything really wrong with the cross
feed other than you had to turn the handle the wrong way to feed the table inwards. That one was 3/4" diameter.
Digital_Hight_Gauge-01.jpg Assembly-01.JPG Adjustment_Arm-05.JPG Nut-01.JPG Nut-02.JPG
The above pictures show the original hight gauge and then the modifications to allow precise adjustments to it. The last two pictures are of the acetal nut after machining and ready to press into the adjustment bar.Best Regards:
Baron J.
Similar Threads
-
Cutting Speeds and Feeds
By KBs PensNmore in forum METALWORK GENERALReplies: 0Last Post: 21st Nov 2017, 03:49 PM -
Material selection help
By Lyle in forum METALWORK GENERALReplies: 2Last Post: 17th Jan 2014, 04:11 PM -
VFD / VSD selection help
By Ironwood in forum METALWORK GENERALReplies: 5Last Post: 21st Aug 2011, 10:45 AM -
material selection
By mick A S in forum TRAILERS & OTHER FABRICATED STUFFReplies: 3Last Post: 17th May 2011, 10:41 PM -
Cutting speeds
By Buncha in forum THE HERCUS AREAReplies: 0Last Post: 13th Oct 2008, 10:53 PM