Project Assembly

[Ji Gantor]

Now that the overall shape has been turned I need to part or seperate the divider washer off the bar.


Ji

[Lozza]

A small machining tip, hunt around on ebay for reamers they have a better fininsh than boring bars and more accurate aswell. Boring bars flex and make the saddle on the lathe move(why they will cut on the way out).Reamers make a straight concentric bore because all the loads are on the centreline of the lathe.You just do the last 1mm or less with the reamer.
Keep up the good work.

[Ji Gantor]

Hi Lozza,
That is gold.
Thanks for your contribution.

Ji

[maicomc490t]

Some hints from an ex toolmaker who knows bugger all, lol.

Even when using a reamer, for accuracy bore out the hole first. This will ensure the bore is concentric as drills can occasionally run off centre and the reamer will then follow that hole (a reamer is a sizing tool not a de-facto drill. Also beware they can create an oversize hole in certain situations - rare but possible)

Reaming speed is usually 1/6 of normal cutting speeds and the feed rate (the speed the tool passes through or over a job) is higher than when using a drill.

The finish of the bored hole doesn't have to be too flash and should be approximately .5mm undersize (.015' - .020") and like everything in life too much lubrication is never enough!

Always use a proper machining lubricant such as Trefolex which ensures good surface finish and longer tool life. For aluminium kerosene also works very well.

If reaming a blind hole (ie a hole which doesn't pass through an object) try and drill deeper than the required reamed depth by a few mm.

If excessive deflection of a boring bar occurs you may have too much play in the cross slide and compound slide which can be adjusted on most lathes. The conventional saddle running on V ways normally doesn't budge. Old lathes may also have wear in the headstock bearings causing deflection.

When using a boring bar try and use the largest available for the job. If the machine is solid and the tool bar is solid deflection will be bugger all. Irrespective of carbide insert bars or high speed steel the cutting edge must be maintained to optimum cut or deflection will occur.

Hope this and Lozza's posts help things along and Ji keep those posts coming !!!

Dave Mac 

[Ji Gantor]

Gold, Gold, Gold

Thanks Dave.

I should let people know that I am not a Fitter and Turner. I have completed one course at a TAFE College covering milling, turning and cutting of metals. Through the course of this topic I am only showing what I have done with the tools I have available. This does not mean that this is the only way to get the job done as we have seen from Lozza and Dave.

The divider washer in my case does not need to have an exact bore so a drill would have been okay but I only have a 19mm and a 21mm so I had to use a boring bar. I don't have reamers but I have used them before on bushes that had to be very accurate. They work great but a bit slow as they are not calibrated and I had to keep checking the diameter. On my job I just checked and I would have had to use two reamers to go from 19mm to 20mm. The job would have been smooth if I did use a reamer.

Thanks Lozza and Dave very fine contributions to this topic.

Ji

[Lozza]

Dave, Dave,  Dave if your off centre use a D bit , for ali get some 'Relton A9' which is far better than kero and stops any build up on the tool especialy 6060(6000 series in general), sounds like you used adjustable reamers, chucking/machine reamers are a set size.Although adjustable reamers have a nice feature, of being able to 'clamp' a bore run it between centres and machine an OD concentric to the bore.Helpful for very thin items that can't be held in a chuck. Should shout yourself a deburring tool also(if you don't already have one)
If your at all interested in home type machining start buying 'Model Engineers Workshop' will teach you much more than TAFE ever will, Harold Hall's books are very informative also

[firko]

Always use a proper machining lubricant such as Trefolex

Call me a weird old old nostalgic but I love the smell of Trefolex....nothing like it.

[maicomc490t]

Hey Lozza - I did say at the start I know bugger all !!!

I was just generalising for Ji as most hobby guys don't have the need to 'tool up' rather than make the best of what they already have eg kero. Full marks for suggesting mounting thin wall stuff on a mandrel - always a good solution to thin wall which can also get chatter very easily.

Everyone should have a de-burring tool - seriously ! At the least a small triangular file can be ground down - I still use the ones I made as an apprentice including one with a carbide insert for one edge. Check out Aussie ebay # 110388119447  or 260411971566   

Hey Firko - you need help ! The smell of Trefolex still reminds me of early mornings riding to work on my 750S, filthy machine shops and trying to wipe the green goo off jobs, lol - still wouldn't swap those days for anything!

Dave Mac 

[Ji Gantor]

When parting off such a large lump of steel always use a live centre or you will have to buy another parting insert.
The tool behind the dividing washers is a deburring tool.

Ji

[Ji Gantor]

The two new shiny dividing washers are now ready to be installed.
I could polish them to a smooth finish but there is no need.
I will turn up another pair out of stainless steel but that will be after CD6.

Ji

[Ji Gantor]

Test fit dividing washers onto the pivot pin.
Looking good.

I don't know Lozza, I think my TAFE lecturers did okay, God rest their soles.

Ji

[oldfart]

Ji,  looking good       what model lathe are you using ?

[Ji Gantor]

Hi Oldfart,
My lathe is a cheap Chinese one.
The most important thing about lathe's is knowing how to use them and having all the tools, otherwise they just spin stuff.

Ji

[evo550]

Ahhh Ji,
I wish all students where like you, I'm a TAFE teacher and 99% of students don't give a toss........let alone turn up for class

[Ji Gantor]

Hi evo550,
I did my Associate Diploma at the South Brisbane campus back in 1981. The buildings were old but had great facilities. Our lecturers were all in their 50ties and all were respected men in their fields. Yes they were paid to be there but most were dedicated to helping those that truly wanted to learn. Our metal workshop lecturer was a gun welder, turner and millist. During our first session he showed us what he could do and I was amazed by this old fellows talent, I was only 18 at the time. He then told us if we wanted to pass this course we would all have to be able to do the same. I absorbed a life time of knowledge from that man over the next 6 months. I never once saw our teacher make fun of a failing student nor not answer a question. He guided 30 students to pass the course without anyone getting hurt boy or girl. During that 6 months not one student dropped out. The college went on to become part of the Queensland University of Technology or QUT just after I finished my Ass Dip.

To show disrespect for these fine men would be to disrespect myself. I could not do it. There are only a few people in this world that will teach you stuff over your life when you look back. Your Mum and Dad, first grade school teacher, the person that shows you the ropes at your first job...

I have been very lucky that others have taken the time to show and share with me their experience and talent and for that I will always be grateful.

Ji