Building a Muncaster entablature engine

[crueby]

just an idea when using a boring bar........could you make it extra long so it fits inside the bore of the headstock mandrel. it could have an oilite  bush on the end and this would stop any deflection ?? !!! I have not done this myself ...just a bit of inspiration...thinking inside the box/mandrel !!!

Then how would you move it out to take a deeper cut?

[steam guy willy]

ok, the boring bar shaft would be operated by the tailstock and the actual device would be attached to it. The adjustment would be affixed to this with a cunning sort of device that would allow adjustment to take place ??????!!!!!!! the depth of cut would depend on the travel of the tailstock ? I have seen boring bars with micro adjustments actuated by a grub screw somewhere.....anyway just an idea !!! i could draw something up perhaps. 

[Jasonb]

I think I used a smaller 2 stone hone on that size cylinder my smaller 3 stone was a bit too tight a fit, bit of paraffin or WD40 will help flush out the muck and stop the stones clogging. They don't take off much so aim for as good a finish off the tool as you can.

Until the drawings have been proven I'd prefer if you don't put up a whole page as pdf, happy for a photo of part of a drawing to illustrate a particular point. However this is a 3D pdf of the cylinder for those interested, may have to trust the document, plus an image of the finished cylinder.

[Jim Nic]

Peter
The hone that you show from Amazon is just the same as the one I have apart from being a lot more expensive! 
The cheapest on e-bay today is £6.91 with free postage for the same thing, and let's face it they are probably all made down to a price in the same factory but good enough to do the job.  Just search for "car brake cylinder hone".
Jim

[steam guy willy]

hi Chris,  here is a drawing of a boring bar attachment !! the tool holder slides on a parallel offset part of the bar with a keyway to keep it in place . There are two threaded collars that may be made in two parts to facilitate attaching to the main tool holding bar part. One of these collars is graduated to adjust in mm or inches. the tailstock end can be held in a chuck or morse taperized. the headstock end could have an oilite bush on it to engage in the mandrill bore. !! just a suggestion if anyone cares to make one !! this tool might exist actually ?? but never seen one. Now lets get back to actual swarf production !!!!

[Jasonb]

The main downside I can see is that you will have to hand feed with the tailstock rather than use the leadscrew or feed shaft to move the carrage under power. If you want to support both ends of the bar then why not just use a between ctrs bar with the work on the cross slide?

[steam guy willy]

The main downside I can see is that you will have to hand feed with the tailstock rather than use the leadscrew or feed shaft to move the carrage under power. If you want to support both ends of the bar then why not just use a between ctrs bar with the work on the cross slide?

Yes good idea....but you still need to adjust the depth of cut of course and this might be a good way of doing that ?

[kvom]

I found the ME article on this engine here:  http://www.replicaplans.com/MuncasterModelEngines/muncaster-07.pdf

Did you find detailed drawing elsewhere, or are you deriving dimensions yourself?

[Gas_mantle]

Hi,

Many thanks for the advice :-)  I'll buy a hone on ebay as suggested.

Kvom, the plans are a set that Jason drew up but I think based on the engine you mentioned.

Thankfully after a bit of tinkering round with the angle the boring bar was set at I started getting a decent finish.





The part is still about 4mm too long so before doing the other end I decided to mill it close to size to reduce the amount of interrupted cuts in the lathe.



Centreing with a DTI before turning the end flange.



Well, the bore isn't blurred while the chuck is spinning so it must be central 



I decided to drill the steam ports next but will leave the steam chest stud holes till I've I made the chest.

1 central exhaust at 3.8mm dia and 2 3mm dia holes located 6mm either side of the centre as steam ports.



Using a wiggler to locate the mill spindle and a quick check with a rule confirms the required 9mm depth won't come crashing through the cylinder wall 





Rotating the part 90^o but keeping the same face against the solid jaw of the vice keeps the part at the right setting to drill the steam passages at either end, all I need to measure is 3.5mm in from the cylinder bore.



With both passages drilled to meet the valve face ports all that's needed is a 3mm wide 2mm deep slot to admit steam to the cylinder



With steam passages now drilled I end up with this and mark out the waste to remove between the end flanges.



Milling away the waste.



Nearly there on one side.



With both sides done this is the result so far.





So far so good  The next job will be to mill a curved back concentric with the bore on the face opposite the valve face



Peter.

[b.lindsey]

Moving right along Peter. The cylinder looks good!!! 

Bill

[Jasonb]

A bit more about the engine and origin of the drawings.

The general arrangement drawing in Kvom's link and a very short description first appeared in a booklet my H. Muncaster entitled "Model Stationary Engines" published in 1912. A reprint is still available from Tee publishing ISBN 0 905 100 263.

I have made it slightly larger by using the ratio of 1mm = 1/32" and drawn it in metric using in the most part whole millimeter sizes and stock materials rather than imperial sizes expressed in metric and going into several decimal places to try and keep with Muncasters original "simple" theme. All the parts have also been kept as simple as possible but with enough detail to avoid the bar stock look, more (or less) detail could be added by the builder if they choose.

There are several nice engines in the book but I have never seen any of them modeled even though the ME articles have been readily available on the net for a number of years, maybe most people are happy just to build to published working drawings rather than put in a bit of effort and make something unique.

J

[Gas_mantle]

Hi,

The next stage is to cut the rounded cylinder back and hopefully end up with something looking like a casting.

There is still a lot of waste on the side opposite the valve face so I start by milling that away.



In order to cut the curved back I need to set the height of the milling cutter equal to the parallel side faces to ensure an even blend, once this is done I zero the depth reading.



Then start milling away between the flanges to the zero depth



Time to start rotating the part and skimming more off at the same depth setting



I've used this technique before when making the rounded tops on bearing blocks and it can give good results, it takes surprisingly few cuts to get close to a rounded profile.  I think I made about 12 passes and I'm happy that the curved area meets the parallel faces in line with the bore centreline.



Time for a bit of Yorkshire muscle power 



Which very quickly takes me to this





Possibly a little more to come off in places but it's starting to look like an engine cylinder 



All it needs now is drilling and tapping for studs but I'll do that after I've made the cylinder cover and steam chest.

Peter.

[pgp001]

Peter

Will you slow down a bit please !!
Some of us need to catch up with building an engine or two before you go racing off making another one 

If you need to use a small cylinder hone, let me know and you can use mine if you want to borrow it, not just sure what size it goes down to, but I think it should fit.

Phil

[Gas_mantle]

Phil, thanks for the offer of using your hone, I may take you up on that - this is a 24m cylinder.

Onwards and upwards I decided to tackle the cylinder top cover next. It is made from the same 50mm sq cast iron bar as the cylinder and first job is to turn a 18mm dia boss 8 mm deep that will support the piston rod and hold packing material. The piston rod hole is stepped with a wider hole at this end for the packing and needs to be drilled from this side.



With a decorative recess cut it's time to part off.



But this parting tool is easier 



Once turned over I want to get the part centred as good as I can because I will drill the piston rod hole from this side later.



A 0.8 mm deep locating spigot is now turned to fit the cylinder bore and the overall outside diameter taken down to size. The diameter is slightly larger than the cylinder flange to allow for wood cladding of the cylinder.



Seems to fit ok.



Happy with the spigot I drill and ream the 4mm piston rod hole. I'm not sure if drilling from both sides is the best way to do this but I like to drill the piston rod hole while cutting the locating spigot and it seems to work ok.



A bit of emery paper gets me to this.







The oversize cover will allow for cladding to be added later. The finished engine doesn't show a bottom cylinder cover and the cladding reaches down to the base plate but I think I'll probably add a bottom cover.



Peter.

[pgp001]

Peter

You are going to need a bigger boiler if it is 24m bore 

I just checked my three legged hone and it will go down to approx 3/4" bore. But wait......you are going to need a bigger hone as well 

Phil