Rear toolpost for parting tool

[thaiguzziParticipant @thaiguzzi]

Posted by clogs on 19/07/2018 08:23:32:

just asking…..

is a rear tool post better than the front sort……I was under the impression that it was better for the smaller lathes…..

IAN's SC photo shows a monster lathe with 1……..

reason:-

I'm still not happy with the parting off results on my Student 6" sqaure top lathe………have tried tipped as well as HSS, best results so far are with a Co/Hss with a slight groove on the top edge like Mark Rand…….

to the point if it's bigger than 35mm I'll use the band saw and then go back to the lathe, the small stuff just use the hack saw…….

and before u ask all the gibs are tight and well adjusted, saddle locked, high speed and plenty of pumped coolant…….I make high speed the next speed up in the gearbox from the turning speed…..ie. if I turn at 500 the next up may be 800rpm……..the high speed parting seems more reliable………

just sick of buying new tipped tool holders…..did make my own parting tool holder that sit's right next to the mounting stud for the tool block……but it's a faf to take it on and off all the time…….main tool holder is the Dickinson type….always thought that the parting tool with the Dickenson holder was to far out, away from the body…….

be interested on ur thoughts………

 

 

 

 

 

 

 

 

 

 

Strange.

I never ever had parting off problems on my two 6" Roundhead Students. My parting off chatter problems only first appeared post Colchester ownership with my current Boxford VSL.

Both lathes ran/run a Dickson style tool post. I always wind the top slide back on the Boxford so the tool holder sits more central over the cross slide which seems to help. This was never neccessary on the Colchester.

Would be interesting to see a photo of your parting off tool holder.

Edited By thaiguzzi on 22/07/2018 06:16:19

[OuBallieParticipant @ouballie]

Mine still being developed.

Works well with aluminium and brass BUT not tried steel yet as overhand may be a bit too much.

Will move the holder further right.

Geoff – if it goes bang on steel I'll know!

Edited By OuBallie on 22/07/2018 11:15:48

[MuzzerParticipant @muzzer]

FYI – Cutwel are offering a free blade if you buy 10 Korloy inserts. That works out at about £65 inc vat for a blade and 10 decent inserts. Note they also sell "H01" grade for parting off loominum.

Be aware that these blades require a holder. However, it's an industry standard system so you could use one from elsewhere. Or make your own.

Murray

[Niels AbildgaardParticipant @nielsabildgaard33719]

Strange.

I never ever had parting off problems on my two 6" Roundhead Students. My parting off chatter problems only first appeared post Colchester ownership with my current Boxford VSL.

Both lathes ran/run a Dickson style tool post. I always wind the top slide back on the Boxford so the tool holder sits more central over the cross slide which seems to help. This was never neccessary on the Colchester.

Would be interesting to see a photo of your parting off tool holder.

Edited By thaiguzzi on 22/07/2018 06:16:19

A Boxford part of system capable of 125 mm alu and 100 mm mild steel

https://www.homemodelenginemachinist.com/threads/selecting-and-using-tungsten-carbide-partoff-tooling-long.10176/

I never got round to making a rear,upside down version as my crosslide had no T tracks

[thaiguzziParticipant @thaiguzzi]

Posted by Niels Abildgaard on 22/07/2018 17:25:47:

Strange.

I never ever had parting off problems on my two 6" Roundhead Students. My parting off chatter problems only first appeared post Colchester ownership with my current Boxford VSL.

Both lathes ran/run a Dickson style tool post. I always wind the top slide back on the Boxford so the tool holder sits more central over the cross slide which seems to help. This was never neccessary on the Colchester.

Would be interesting to see a photo of your parting off tool holder.

Edited By thaiguzzi on 22/07/2018 06:16:19

A Boxford part of system capable of 125 mm alu and 100 mm mild steel

https://www.homemodelenginemachinist.com/threads/selecting-and-using-tungsten-carbide-partoff-tooling-long.10176/

I never got round to making a rear,upside down version as my crosslide had no T tracks

Yes, thanx for that, but i'm determined to persevere from the front, using both HSS and tipped tooling. If it worked on a Colchester (yes, i know, mass & rigidity etc), i'll be damned and eventually make sure it will work on a Boxford. No problems on 30-40 mm alloy etc, but the same cannot be said for steel or S/S in the same OD.

I was always under the impression that rear toolposts were designed for Myfords, with their flat ways, and saddle design….

[S.D.L.Participant @s-d-l]

Posted by thaiguzzi on 23/07/2018 06:08:48:

Yes, thanx for that, but i'm determined to persevere from the front, using both HSS and tipped tooling. If it worked on a Colchester (yes, i know, mass & rigidity etc), i'll be damned and eventually make sure it will work on a Boxford. No problems on 30-40 mm alloy etc, but the same cannot be said for steel or S/S in the same OD.

I was always under the impression that rear toolposts were designed for Myfords, with their flat ways, and saddle design….

Two experiances that may be related

We had a Colchester Master at work with a rear toolpost carbide insert upside down, reasonable machine but when I tried to part of a load of M24 A4 stainles steel bolts (316) by hand feeding as i worked in design normally but i needed these for a Factory acceptance test the next day, it kept digging in and breaking the tip. This was only cured by using power feed then I did about 50 of them easily.

Now days at home I have a MKII Colchester student, using a front mounted T2 Dickenson toolpost and a Sandvik inserted blade I had digins, changed the toolpost to a create multifix copy now goes through 316L like butter, best on power feed but can do it by hand if you keep cutting.

Couldnt see angy damageon the Dickenson toolpost but the multifix seems far more rigid,

Steve

[Clive FosterParticipant @clivefoster55965]

In my experience many Dickson problems are due to folk not cleaning the innards. They pop apart very easily so no great issues there. If they have not been done for ages its amazing how much stuff gets inside. Don't for get to brush off the mating surfaces of holder and post before insertion. Its important that the adjuster stud is straight and that the collar is a free fit in locking nut slot.

Brand new or properly scrubbed up clean there is little difference in holding power and rigidity between a Dickson and a Multifix. Factory fresh Multifix will beat well used Dickson set which, almost invariably, have bent adjuster studs due to years of mishandling. Correct technique is to hold the tool carrier up against the post. Pulling into position vial the locking cam eventually bends the stud. However Dickson does have inherently more overhang between tool tip and centre bolt so if not properly bolted down or retrained by the locating pin it is more prone to rotate under cut. Cost me a parting blade to learn that!

Clive.

[mechman48Participant @mechman48]

I have a rear tool post made from a kit & it works fine after a couple of mods; ( see my album; rear tool post ). I also have the x slide tool post wound back along the compound slide to allow more support under the tool point ( rigidity )…It also helps part off under power feed quite easily as it allows the parting tool to locate nearer the centre of the cross slide.

George.

 

Edited By mechman48 on 23/07/2018 14:03:32

[JonParticipant @jon]

Posted by Muzzer on 22/07/2018 13:31:16:

FYI – Cutwel are offering a free blade if you buy 10 Korloy inserts. That works out at about £65 inc vat for a blade and 10 decent inserts. Note they also sell "H01" grade for parting off loominum.

Be aware that these blades require a holder.

Great price that Murray, Korloy are good tips so is the blade holder a bargain.
Have same tips and two tool holders from a global class producers both dig in or bind up no warning coolant or not often scrapping the job or breaking the tool and tip.

Have think 9 part off tools all quality along the lines of Iscar, Seco etc. 2.2mm MGMT first point of call up to 35mm dia, face off, turn, groove and part with them.

[Clive FosterParticipant @clivefoster55965]

Jon

Last couple of parting blades I broke, one HSS, one tipped, were due to tool post pivoting fractionally on deep jobs forcing the blade to bend. Which tends not to be good thing at 2 or 3 inches or more depth of cut.

Looks like I shall have to either finally make a rear tool post for the 1024 or drill the topside for the Dickson location pin.

Using Rocol synthetic coolant probably doesn't help as the silvery component gets everywhere. Stays too. Too serious scrubbing to get the chuck jaws properly clean and grip back up to what it should be.

Clive.

[HopperParticipant @hopper]

Posted by thaiguzzi on 23/07/2018 06:08:48:

 

 

…I was always under the impression that rear toolposts were designed for Myfords, with their flat ways, and saddle design….

Not really. I think the idea came originally from many industrial capstan lathes that commonly used a rear parting tool and was picked up by early model engineering types who were exposed to such machinery at their day jobs.

Certainly easier to implement on a Myford with T-slotted cross slide than Boxford's Yankee-style slide.

I've tried both front and rear parting tools on my Drummond and Myford and definitely the rear works best. Whether that is due to the chips falling out of the groove or the spindle forces being directed downward into the more solid half of the headstock bearings is a debate that rivals oil choices and will probably never be solved.

But at work years ago we always used front parting tools, normal way up, but that was on large industrial lathes of top quality (DSG, Monarch etc) in good condition, with plenty of coolant flowing. I don't remember ever trying to part off jobs over 2" diameter, in other words the same size that we are today trying to do on relative tiddlers of machines such as Boxies and Myfords.

As usual, model engineers are forced by necessity to push their machines to ridiculous limits and beyond.

Edited By Hopper on 24/07/2018 02:31:37

[thaiguzziParticipant @thaiguzzi]

# My Dickson (genuine Bison copy) is dismantled and cleaned a couple of times a year. The first time i did this was prolly after 10 years of ownership – could not believe the crap in there…

# The tool post has a location peg/hole in the top slide.

# i have learnt to have the part off tool over the cross slide – this does help.

# Cross slide is a t slot type with longer dovetails than the stock "Yankee style". It's not on the top of my list of Things To Do, but maybe, one day, i'll get around to making a rear tool post. In the meantime………..

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