Member postings for Marcel Jolinon

Having read all this I am considering a slight shift of the cylinder away from true, It would be such a small deviation so hardly noticable if at all. Havn't got round to the cylinder yet.

JA,

We always used to work to function follows from, and if it looks right it probably is.

I am quite sure Watt and his engineers/draughtsmen never went to these extents, however if they had had the tools, computers etc that are available today I do wonder if they would.

We have the benefit of their trial and error, and clearly as a result of their over engineered machines which have lasted to the present the benefit of their efforts. More than can be said of modern practices which par evrything down to the bone.

I have yet to visit the Crosness pumping station which is supposed to be a work of art.

Edited By Marcel Jolinon on 07/02/2023 12:39:41

Edited By Marcel Jolinon on 07/02/2023 12:42:02

I am working on drawings at the moment. I can't get out to do anything in the workshop for a while, probable 3 to 4 weeks but when I do I have to finishthe air intake for the car and put the exhaust back on. The management wants household repairs done as well. This is a future project.

I can sit at a desk and use the computer thought.

That was exactly the problem, they were not the best drawings either.

As an excercise to learn CAD they were good enough. Then OCD raised its head and I thought I would correct the errors. I am now pretty well starting with a new design but trying to retain the original concept of the tripple B engine to make it from barstock but doing a metric conversion.

Wow! I didn't expect such a response.

I have placed the geogebra file in dropbox, hopefully this link is right.

https://www.dropbox.com/s/kttam2grz1bk6id/MJengine1.ggb?dl=0

Anyone playing with this will need GeoGebra installed. It is supposed to be a teaching aid, but I think it goes way beyond that.

I did start out with a 60mm stroke but have since shortened it to 52mm to get rid of the biggest error at the bottom of the stroke.

This started out as an exercise to improve my skills with Turbocad and I was re-drafting some drawings I found on the net. During the process I found some anomalies so thought I would check them, that is when I found GeoGebra as a maths program. I am now well and truly down the rabbit hole and have the ambition to build this engine when I am back on my feet and in the workshop.

The piston rod would be 98 mm long SS plus the piston thickness.I am working on a diameter of 5.5 mm to 6 mm.

The error is 0.19mm right at the bottom of the stroke and is down to 0.04mm after 60 Degrees of crank rotation which equates to 5mm of piston movement. At 254 Degrees the error is -0.05mm and at TDC 0.09 mm.

I have placed 4 screenshots of the model in my Beam engine album.

I am wondering if or how I could post the actual file. I have set it up so that I have options to adjust the various linkages. This may be of interest to others on here.

What would be an acceptable amount of lateral movement in the piston rod for a beam engine?

I know the Watts linkage does not produce a perfect vertical path, I have moddeled the linkage and can get the error down to to less than 0.19mm (0.0075 ins)

Would this be an acceptable error on an engine with a stroke of 60mm in a 22mm bore ?

I have moddled the motion in GeoGebra but I can't post the file on here.

I have entered the dimensions in to GeoGebra and created an animation of the motion. Given the published dimensions the piston will hit the lower cylinder head and the Watts linkage is out of alignment and the piston rod will bind.

I have been over the numbers several times, and have now begun to question my drawings

What started out as a drawing to get to grips with Turbocad has taken on a whole new dimension. I would be interestd to know if anyone has tried to build that engine from those drawings.

It is a pitty I can't post the GeoGebra files on here, I think some may find the excercise of interest and I also thing there is some use for this app. If anyone wants to have a look at the workings I can email them.

Now that is intereting. JDW appears to have scaled the drawings up by a factor of nearly 1.5:1 but seems to have done some rounding on the conversion. I think this may be the reason the Watts Link is out of kilter and does ot follow a perpendicular path, but I may be wrong.

Having read the thread in the above link, and I have no idea why my searches didn't show that website, it would appear that those who have built the engine have not encountered problems with the linkage jamming up.

This has prompted me to look further into the linkage for the valve timing, currntly getting stuck with the moddeling.

More to follow.

Edited By Marcel Jolinon on 19/01/2023 19:23:19

I have spent some time trying to track down the originals, apparently a design by Bob Holme, but not found anything yet.

That was supposed to read less than < so the deviation from vertical is < 0.1mm and that is at the extremity of travel.

And the diagram was supposed to be moving. It was generated by GeoGebra, a maths tool which is really good, but took some working out.

Jason,

Julius? Would that be J.A.M. DeWaal in NZ?

If so those are the drawings I am re-draughting. It started out as a learning project for Turbocad whilst I am laid up. I have already discovered the errors in the linkage geometry and have got the tracking error of the top of the piston rod to >0.1 mm

I have also noticed that the link rods are shown as being pinned together on one of the shafts, this will stop the links rotating independently and the bushing arrangement is not satisfactory.

Edited By Marcel Jolinon on 12/01/2023 11:10:12

Does anyone have any experience of this beam engine.

I have some drawings which I found on the internet, however they are not very good, I have started to re-draught the plans and there are a number of errors and omissions which I have found.

Initially this was a Turbocad learning exercise, but I may build it when I am back on my feet.

I go with ACF50, and a rag which I keep specifically for the job is soaked in it. A good, regular rub down is all that is needed.

Most of us have draughty, inadquatly insulated and heated workshops so hve to make the best of what we have.

Hi Pete,

I have striped the machine down twice. No swarfe on anyof the slides.

Visual inspection with a straight edge and feelers leads me to think there is no apreciable wear, also normaly when wear is present it tends to be in the centre of the slides, or with lathes up near the headstock. My old Brown and Sharp lathe was pretty bad. When the gibs were adjusted up near the headstock it would jam up towards the tailstock.

This is not happening with the milling machine, which also leads me to think it is not a wear related problem. Also I believe that the slides are induction hardened, like the lathe beds, so almost impossible to scrape I think.

There is a gap (clearance) of around .9mm on either side between the knee and the slide, clearly there by design. The gib strips pull the slide down. I have adjusted the gibs again last night, the action is now quite tight and the twist has gone. However to me it seems too tight. I dont supose anyone knows what sort of torque would be required to turn the screw. That I can measure.

I think I am using the wrong procedure for adjustment. I am tightening the adjustment screws one at a time little more than finger tight and locking them up. Should I have all the locknuts slack adjust all the screws and then tightem all the locknuts? Should I be adjusting one side at a time, or perhaps going side to side, or perhaps even diagonally?

As I said I have no idea of the correct procedure for this.

I have now measured the twist on the slide which is reading 0.15mm on my dial gague. I can get no discernable lift though.

It was measured with the table moved pretty well to the end of its travel, I also had the table locked down.

I am trying to move this by hand though. Should I be clamping a bar on to the bed to give some extra leverage?

As said above I do not know the correct procedure for adjusting this. Just been going by trial and error.

I have just added an image but it is upside down. I cant find out how to resize it or rotate it.

Edited By Marcel Jolinon on 21/01/2019 23:17:06

Edited By Marcel Jolinon on 21/01/2019 23:18:15

Edited By Marcel Jolinon on 21/01/2019 23:27:07

David, Pete,

Thanks for the input.

Centralising the bed? I can't get the bed to lift, but it does twist. are you suggesting that if the side furthest from the Vee is tightened first it will lift the other side of the bed slightly? It is a heavy old lump.

Initially I had the table (X Axis) off of the machine when I set the Y axis gibs and it was fine for a couple of passes. i have singe tightened up the gibs twice, I did it again this afternoon. the twist has gone for now, but if past experience is anything to go by it will re-appear.

All the ways appear to be true, as best as I can tell with a straight edge, and running the slide ove with blue does not show anything untowards. I dont think it is a wear issue as past experience has shown if gibs are adjusted in on position they have a tendency to bind at a different point on the ways, conversly if they ar tight a one spot they are slack at another. However this problem occures regardless of position.

I must admit I am finding adjusting this machine a bit of a trial, there is nothing in the manual.

Having said that I am going to try twisting the bed with a dial gague fitted to check for lift. That is for tomorow night.

Yes, The axis that moves towards and away from the column. Dovetail on one side only. The left hand side.

Andy Pugh's video of his cnc conversion shows this single dovetail quite clearly.

Good evening all.

On a harrison vertical mill the gib strips pull down the slide on to the knee casting. The axis is controled by vee; raisde on the knee and cut into the slide casting.

With the gib strips tightened so there is no lift the slide still wants to twist and pull itself up the vee.

I cannot get any measurable lift on the slide, but it still twists slightly from side to side. I dont want to flog the gibs down any tighter as I having tried that the motion becomes quite stiff.

Has anyone else experienced this? I have some gib strips out of an old lathe. I am considering milling slots in the vertical sides of the gib retaining slots, drilling and tapping holes and then fitting gib strips to control sideways movement.

Has anyone any experience of this, and another possible solution.

I was taught by to feed gently using two hands, use the ring of the handwheel rather than the knob and keep feeding it through both hands a little at a time. Keeping the pressure even on the transfer is the trick. Like all skills it is a case of practice.