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  1. #106
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
    Age
    71
    Posts
    5,945

    Default

    To grow old is mandatory, growing up is optional.

  2. #107
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Thumbs up Corrected drawing !

    Hi Guys,

    Apart from the lines being the wrong colour on the first drawing, I also found a couple of dimension errors. I've also added note under the turned plastic rod, saying where it goes.

    NOTE: I've not made any attempt to show the threads on the ends of the "T", since I've found that two different makers have used different threads. I suspect that the one that I used could have been foreign made !

    Damper-Control-Valve-01.png
    The corrected drawing. Guys if you spot any errors in this one please let me know. Thanks.
    Best Regards:
    Baron J.

  3. #108
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Thumbs up Hydraulic Cylinder Base Cap.

    Hi Guys,

    One of the things that I needed to make was a suitable plug to fit into the end of the hydraulic cylinder that I'm using for the bandsaw drop damper.

    The outside diameter of the cylinder is 32.25 mm, whilst the inside diameter is 30 mm. I had a 20 mm length of round bar 40 mm in diameter. Ideal for a plug ! However it was far too short to hold in the lathe three jaw chuck in order to turn it down to size.

    Since I had already decided that I might need a drain hole in it. I drilled a 5 mm hole right through on the lathe and then tapped it M6. I've various M6 screws, in steel, brass and plastic, all ones that would be suitable for use as a plug to seal this hole.

    I also had a scrap 30 mm diameter bar end, again too short to do anything other than drill a hole through it. Which I also drilled 5 mm right through and then threaded M6. I screwed a hex head bolt right through and then used the rest of the bolt to screw the piece of 40 mm diameter bar onto it.

    21-10-2019-009.JPG 21-10-2019-008.JPG 21-10-2019-007.JPG
    These are the finished plug and the mandrel that I made and used to turn the plug to size. The plug is a good sliding fit into the hydraulic tube. The lip is there simply to prevent me loosing it into the tube when I weld it in place. That third picture is with the mandrel secured in the three jaw chuck ready to screw the workpiece in place.

    21-10-2019-005.jpg 21-10-2019-004.JPG
    A couple of pictures after taking a couple of cuts. Note that I put a centre into the end of the bolt and used a live centre to ensure support whilst turning.

    21-10-2019-001.JPG 21-10-2019-002.JPG 21-10-2019-003.JPG
    These pictures show a 1 mm depth of cut at 620 rpm and a fine feed.

    21-10-2019-010.JPG 21-10-2019-011.jpg
    After machining the plug, I drilled a 20 mm diameter counter bore that will be on the inside of the cylinder. This counter bore is intended to provide space for the piston securing nut. I'm using a 20 mm diameter blacksmiths drill with a 1/2" inch reduced shank in the tailstock chuck. The plastic wrap is packing so that the chuck jaws don't grip and damage the raised lip on the edge of the plug and ensures that the workpiece isn't canted.

    The hole was drilled to a depth of 15 mm at 160 rpm. The depth being controlled by a M6 screw threaded in 5 mm from the other side. I simply stopped drilling when I hit the end of the screw. I've yet to check whether I need to put a flat bottom in the hole, the cone made by the point of the drill might be enough to clear the piston retaining nut.

    That's all for now. Thanks Guys.
    Best Regards:
    Baron J.

  4. #109
    Join Date
    Apr 2012
    Location
    Healesville
    Posts
    2,129

    Default

    Quote Originally Posted by BaronJ View Post
    Hi Guys,
    21-10-2019-008.JPG
    These are the finished plug and the mandrel that I made and used to turn the plug to size. The plug is a good sliding fit into the hydraulic tube. The lip is there simply to prevent me loosing it into the tube when I weld it in place.
    Hi John, instead of welding that plug in is there enough meat there to put an o ring groove in it?
    And then secure it by a plate across the back bolted to the mounting plate.

    cheers, shed

  5. #110
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Default

    Hi John,

    Thanks for your post.

    That's a good idea ! I've plenty of "O" rings, both imperial and metric sizes. I collared a pair of those boxes when Lidl were selling them off.

    There is about 6 mm or so of wall thickness on that plug, so plenty of room to put an "O" ring, but it would have to go close to the end furtherest away from the flange, because I intend to drill and thread through the tube and plug to take a 1/4" bsp elbow fitting. Which should mean that I don't need to make any additional parts to secure it.

    Pictures to follow.
    Best Regards:
    Baron J.

  6. #111
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Thumbs up Hydraulic Cylinder Base Cap Ready for fitting !

    Hi Guys,

    Following Shed's suggestion, I machined two grooves in the plug for "O" rings ! I used the same mandrel to support the plug as I used to make it.

    24-10-2019-006.JPG 24-10-2019-007.jpg
    I started by making a round nose tool from a broken centre drill to cut the grooves ! At least that was the intention. Then It was pointed out to me that I didn't need or want a close fit for the "O" ring, and that it needed space to move as it was compressed. Therefore The groove should have a flat bottom and not be rounded.

    About 10% or 15% more than the cross section diameter, for the width of the groove was suggested, and the same 10% or so increase in size over the "O" ring bore diameter. So I chose a 3 mm cross section "O" ring that just cleared the bore of the hydraulic tube. Time will tell if I've got it right.

    24-10-2019-003.JPG 24-10-2019-002.JPG 24-10-2019-001.JPG
    These pictures are of the first "O" ring and the initial groove that I machined. I took the plug off the mandrel and turned it around putting it into the chuck jaws to machine the second groove. I copied the size of the first groove.

    24-10-2019-004.JPG
    This is the finished plug with both "O" rings fitted. That "O" ring on the left in that picture is damaged ! I didn't realise that I had nipped it when placing it into the tube. Very difficult to measure but I think that particular "O" ring is a few thou thicker than the other one.

    24-10-2019-005.JPG 24-10-2019-009.JPG 24-10-2019-008.JPG
    These pictures are of the fitted plug with a pair of new "O" rings on it. Its a much tighter fit than I expected. Anyway I've put a sealing screw in the end and about 100 ml of hydraulic oil inside and stood it on end to see if it weeps at all.

    Tomorrow I will put the piston in the cylinder and apply some pressure to see if it leaks or blows the plug out. I hope that neither happens.

    The next step is to accurately drill and tap a hole through the side for the elbow that holds the oil transfer tube. But more on that later.

    Thanks Guys.
    Best Regards:
    Baron J.

  7. #112
    Join Date
    Apr 2012
    Location
    Healesville
    Posts
    2,129

    Default

    Hi John, if your grooves are a bit tight and you are interested in checking your o ring groove sizes you can have a bit of a read here https://www.sealingaustralia.com.au/...groove-design/ there are quite a few websites that have info on o-ring grooves.
    For the small amount of pressure that you will have there i wouldn't be too worried about it leaking, nice job m8

    cheers, shed

  8. #113
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Default

    Hi Guys,

    Well it did leak ! A nice little puddle on the bench top this morning. Also the piston was able to exert enough pressure to push the plug out. I did find that I had nipped the lower new "O" ring again ! That's the second one.

    So in order to make sure that the plug didn't move whilst drilling and threading the M12 hole for the elbow coupling I drilled and threaded three places at 120 degrees for M4 screws. I also made the grooves in the plug slightly wider as recommended in the literature that Shed pointed me to. Doing so made it somewhat easier to fit the plug with the new "O" rings on it. For the time being I've used a nylon M12 bolt to seal the hole for the elbow which is quite a tight fit.

    At the moment its stood on end in a plastic tray with 100 ml of hydraulic oil in the tube. I did force the piston down using my body weight without any sign of leakage. So it looks as if I might have got an oil tight seal this time.

    26-10-2019-003.JPG 26-10-2019-004.JPG
    The drilled and threaded plug ready for new "O" rings. To be honest I don't think that the "O" rings are of the best quality. Some of them have traces of flash on the edges where the mold has not quite closed.

    26-10-2019-001.JPG 26-10-2019-002.JPG 26-10-2019-005.JPG
    These pictures are of the drilled tube and the plug with the M4 screws in it. They are just waiting to be cut down to length. They are brass ones, and the off cuts will be used to make grub screws.

    More later ! Thanks Guys.
    Best Regards:
    Baron J.

  9. #114
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Default

    Hi Guys,

    In the last post I showed three brass cheese head screws and I thought that they were M4 I've discovered that they are in fact 4BA ! So rather than cut them down, I've used three M4 cap crews instead. I hadn't realised how close the two screws were in size, it was only when I tried to screw them into the M4 die that I discovered that they weren’t M4.

    Now on to today’s work ! I've turned a short piece of 13 mm diameter brass bar down to 11.80 mm and threaded it M12 for a distance of 13 mm in order for it to screw into the M12 hole in the bottom of the cylinder. I've also drilled it to take the copper tube and soldered a short length in place to create a spigot that I can use to mount and secure the 90 degree elbow to.

    28-10-2019-002.JPG 28-10-2019-003.JPG
    I've also milled four flats on the brass fitting to take an 11 mm AF spanner. The copper tube is about 6 mm too long in these pictures so I will shorten it before fitting.

    28-10-2019-001.JPG 28-10-2019-004.jpg
    These three parts will fit together and be screwed into the base of the hydraulic cylinder.

    28-10-2019-005.JPG
    This is what it will look like when completed ready for the tube to the flow control valve. Now to start on the other end

    Thanks for following my progress with this project. Your comments are welcome.
    Best Regards:
    Baron J.

  10. #115
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Thumbs up Cylinder other end !

    Hi Guys,

    Slowly making progress with the hydraulic damper. I've modified the existing piston and made a plastic plug to fit into the other end. More pictures.

    29-10-2019_002.JPG 29-10-2019_001.JPG
    I set the shaft up in the four jaw chuck and made sure that it was accurately trued up. I haven't taken any pictures of that since a dial indicator with a stationary needle isn't very interesting.

    However this is ! I was quite surprised by this.

    The piston looks like its a series of four fibre washers with a hard plastic moulded centrepiece. But it's not !
    I started to use a narrow lathe tool, with the idea of removing what looks like a very hard plastic material, but quickly realised that it was metal. In fact it turned off very easily in a shower of fine dust like particles, a bit like cast iron. It seems that this part had been made from very fine particles of metal and compressed into the shape that you see. A little bit like a plastic moulding, which thinking about it, it is !


    29-10-2019_003.JPG 29-10-2019_004.jpg
    When I realised how soft this material was I changed to using my parting off blade, particularly since I had already under cut the nut that I had used to secure the piston to the shaft. I turned the face off until I had a completely flat surface, only leaving enough to prevent the piston from becoming loose. The small lip that was left was quickly removed by using a countersink in the drill press, ensuring a smooth flat face.

    29-10-2019_012.JPG 29-10-2019_011.JPG
    These two pictures show the piston fitted to the shaft with one of the 8 thou thick washers covering the newly turned face of the piston, along with the nut and washer securing it. As can be seen in the second picture the vents through the piston will allow oil to flow through and then flex the flat washer on the other side. Effectively creating a non return valve. At least that is how I hope that it will behave. I used a self locking nut in order the ensure that it did not unscrew whilst in use.

    29-10-2019_005.JPG 29-10-2019_010.JPG
    The first picture is a family one of the nylon plug and the two "O" rings that I'm using. One to act as a shaft seal and the other to seal the shaft support plug when its pressed into place in the cylinder bore.

    29-10-2019_006.JPG 29-10-2019_007.JPG

    29-10-2019_009.JPG 29-10-2019_008.JPG
    These four pictures are of the nylon 60 plug that I turned to fit into the cylinder and support the shaft. The large "O" ring is intended to seal the plug against any oil leakage around it and the small one a shaft seal to prevent oil from leaking around the shaft. I've marked the recess with red marker so that it is easy to see in the picture.

    I'm going to start measuring up to see where I need to make the cut, when cutting the cylinder to length and the position of drill the hole for the spigot and the elbow and its fittings going to the control valve. I also want to do a drawing for this damper for future reference.

    Thanks for your support Guys.
    Best Regards:
    Baron J.

  11. #116
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Thumbs up My Booboo !

    Hi Guys,

    I see nobody noticed my error !

    I didn't until I started to do the drawing for the damper bits.
    Best Regards:
    Baron J.

  12. #117
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Default Damper Drawings.

    Hi Guys,

    This is the drawing for the drop damper for the bandsaw, made using a car shock absorber !

    Damper-Cylinder-02.png
    Dimensions are in Red. The piston is in Yellow. Grooves are in Blue.
    Best Regards:
    Baron J.

  13. #118
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Thumbs up Parting off the cylinder !

    Hi Guys,

    Since it seems that nobody wanted to have a guess at the glaring error that I made, Here are pictures of the before and after correction !

    29-10-2019_008.JPG
    Before !

    03-11-2019-001.JPG
    After ! I got the small "O" ring at the wrong end.

    As it happens it wasn't a show stopper, since I had to bore the plug out at the other end, to allow clearance for the inlet spigot.


    Since the hydraulic cylinder was far to long to use as it was and I only needed 162.5 mm (6.4" inches) of length, I cut the cylinder by parting !

    03-11-2019-002.jpg 03-11-2019-003.JPG 03-11-2019-004.JPG
    I set the tube up in the lathe, using a live centre in the tailstock to support the other end. I then cut a 1 mm deep groove around the cylinder at the length I wanted plus 1 mm to allow for cutting width. I then used an abrasive cutting disc in a Dremal to separate the two halves. A quick rub with a fine file was all that was needed to clean up the cut and de-burr it.

    Next job plumbing
    Thanks for looking.
    Best Regards:
    Baron J.

  14. #119
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Thumbs up Plumbing !

    Hi Guys,

    Plumbing done ! Just a matter of setting it up on the bandsaw itself.

    09-11-2019-001.JPG 09-11-2019-002.jpg
    The plumbing is now done ! The oil flow path is from the top of the cylinder to the bottom via the flow control valve which can be adjusted with a screwdriver and left as set.

    I've still to make the link to the pivot arm on the bandsaw and decide where to attach the mounting plate. The pivot arm has 3" inches of movement and to allow for fitting the hydraulic cylinder has four inches. Because of the seals and bypass tube and its associated parts the overall length is nearer 6.5" inches. The system will be filled with hydraulic oil from the drain hole at the end and then the sealing screw inserted.

    Thanks guys for following along !
    Best Regards:
    Baron J.

  15. #120
    Join Date
    Aug 2006
    Location
    Melbourne
    Posts
    1,105

    Default

    Is there a check valve incorporated somewhere?

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