Cam Grinder on The Go

[Brian-in-Oz]

Thanks Charles - I too am using 5mm HTD timing pulleys (15mm wide) 24 teeth on the master cam and chuck drive. I think I will settle on 12 RPM so off to my local bearing shop tomorrow for a 48 tooth pulley for the 6 RPM geared head motor. Cheers Brian

 

[johwen]

Congtratulations, This is quality workmanship. Love to see the plans as they maybe.

 

[johwen]

I'm building the Westbury Sealion. I have made the camshaft with individual cams locktighted to the shaft. Made with all due care but I'm not satisfied of the overall timing accuracy. I actualy made a crankshaft grinder for the crank and that worked out well.

To drive the crank I purchased a 12 volt geared motor from Jaycar here in Australia about one inch in diameter and 12 foot pounds of torque, more than powerful enough.
Allup about $50 with battery and charger. Turns the shaft slow enough for accurate grinding. Cheers John

 

[ICEpeter]

Charles / Brian-in-Oz,
The cam grinder I built a while ago turns the shaft with the work piece at 10 rpm with good results as far as material removal and surface finish is concerned. I figure 10 to 12 rpm should be optimal.

Peter J.

 

[Blogwitch]

Lovely piece of engineering Peter, very well made indeed, and I am sure it will last yourself and anyone following many years of faithful service.

Unfortunately (there always is) a bit of a hiccup, it seems very complicated for the average Joe to construct for maybe only a couple of camshafts to be made.

In Strictly i/c (sadly been out of print for many years), Aug/Sept & Oct/Nov 1994 issues, there is a fairly easy to build cam grinder that could be knocked up in a few days rather than months if you have the bits knocking about, that will do the job admirably for most peoples needs.
I do have copies on PDF, but I think it might be illegal for me to post the text and plans on here because of copyright.

If anyone wants more info, send me a PM.

John

 

[Brian-in-Oz]

Thanks for your input Peter - have decided to start with 12RPM and trust that will be OK. I hope to get a bit more done later in the week.

 

[ICEpeter]

Hello John / Blogwitch,
Thanks for your kind remarks. You are right, my cam grinder is complex but it serves other purposes as well besides cam shaft grinding. It allows multi cam camshafts of up to 225 MM (9 inch) to be ground and also allows the grinding of crankshafts with a throw of up to 32 MM ( 1 1/4 inch) as well as cylindrical grinding of up to 50 MM (2 inch) by 225 MM (9 inch) long pieces. Short pieces of dia. 100 MM (4 inch) by 50 MM (2 inch) long can also be ground as well as individual cams of various diameter and length. Have used it in the past to accomplish all the previously described operations and am quite happy with the results.
I agree its complex and it was not a matter of days for construction, more like 2 - 3 months to build. But what the heck, what is time when you are having fun building.

Peter J.

 

[Blogwitch]

Peter,

I wasn't criticizing you or your work at all, you have done a wonderful job, and like everything else, each to his own.

All I was trying to do was to maybe dispel a few fears that to make a camshaft grinder doesn't take months of work and large amounts of pocket money, and if someone can build an engine, they should be able to construct an easy to make cam grinder to put into their engine.

I was actually going to make one, but found that I could make my cams to an acceptable standard using ETW's methods to cut the flanks on a lathe, it did the job to a standard that was acceptable to myself.
The only problem with ETW's method is that you harden after machining rather than before with a cam grinder, and things can sometimes not go quite right..

John

 

[Brian-in-Oz]

Hi all - cam grinder is coming along nicely. About the only things left to make are the master cam follower (tomorrows job), a locating keyway on the master cam shaft, positioning collars for the rocking arm linear bearing, a terminal switch box for the motors,a guard for the grinding wheel and a bit of cosmetic tidying up. At the moment it is mostly in bits so a photo not available at this stage (soon) but have attached a pic. of the micrometer stop for lowering the rocking arm as grinding a cam progresses.
Making this was an interesting exercise in its own right and I am quite pleased with the end result. It is made to the Imperial standard 40tpi with 25 one degree increments per revolution.The travelling "nut" with an internal 40tpi cut on the lathe to specs. was made to a firm finger push fit into the cylinder and then lapped with some 600 valve paste I bought to lap the valves in the Edwards Radial so it is a nice smooth sliding fit with no play. The next challenge was to cut the 40tpi thread to fit the "nut" so that it turned smoothly with no backlash so lapping paste to the rescue again. I made tiny final cuts until the "nut" screwed on hand tight and then lapped the thread by spinning back and forth on the lathe
by reversing direction and the whole device spins as smooth as my Starret without any backlash.
Of course lowering the beam say 12 thou. will lower the grinding wheel only 3 thou. because of the 4 to 1 reduction ratio. I think making a conventional outside micrometer would be a nice personal satisfaction engineering project but from a practical point of view a bit pointless.

I will follow up with some more pics. soon- Cheers Brian

 

[Brian-in-Oz]

This is the master cam follower. It attaches to a sliding vertical adjuster. The relief on the LHS is to provide clearance from a rear chassis cross rail in case it is ever needed to grind a large cam. Apparently a flat follower would work OK but I decided to grind the optimum 4 x the radius of the grinding wheel in this case 20 cm. on the contact sole.

Cheers Brian ;D

 

[Brian-in-Oz]

Hi all - here's some pictures of where I am at. Not a lot to do but still some hours for me. I want to give a bit more downwards adjustment of the spindle to accommodate grinding wheel wear, slot the master cam drive shaft to keep master cam calibrated, a grinding wheel guard, grinding wheel dresser attachment and wire the motors with switches. The weather has been cold and wet so a good inducement to stay in the workshop.

Cheers Brian scratch.gif

 

[Brian-in-Oz]

Hi all At HMEM - my design it as you go cam grinder is now complete.
It has been an interesting exercise in coming up with design solutions for each step as the project progressed. In an attempt to ensure that the contraption might actually work when completed I have incorporated as much adjustment as possible to the components . i.e vertical movement on the spindle to accomadate grinding wheel wear - chuck calibrated 360 deg. for timing cam lobes - master cam drive shaft adjustable to "lock in" any required settings for cam being ground - cam follower adjustable an well as adjustment on the cam follower mount - micrometer adjustment in .001 inch to lower rocking beam as cam lobe grinding progresses - because of the 4 to 1 reduction ratio of the beam a 4 thou. adjustment at the micrometer calculates to a grinding "cut" of 1 thou. -
rocking beam adjusts laterally on a linear bearing on a hardened ground shaft to move from one lobe to another and is locked in place while grinding with a collar with grub screw on each side of the linear bearing - micrometer slides and locks into position as each lobe is being ground. The cam being ground rotates at 12 RPM and the grinding wheel at 6000 RPM and rotating in opposite directions. A camshaft up to 11" long can be accomadated and the maximum lobe rise from centre is .600". (maybe if this thing works at all I can recoup a few bucks grinding hot cams for the motorcycle "cafe racer sect" - only joking!).
I also need to put together a diamond wheel dresser but this is relatively simple and should not take long.
At this stage I have not decided what the next engine project will be but am leaning a bit towards a flat four or six. Unfortunately this will be postponed a bit into the future as SWMBO has presented a daunting list of household jobs.
I will however try to sneak in a test cam grind and some pics in the near future.
Below are some pics of my "Heath Robinson Contraption" and if it actually works and grinds a nice cam only then can it be called a CAM GRINDER.

Cheers Brian - :hDe:

 

[Charles Lamont]

Looking good.

 

[Charles Lamont]

I think wacky machining setups are always worth a photo and a post. Here we are milling the 12.3" radius on the delrin cam template follower shoe. This radius (5 times that of the grinding wheel) is needed to maintain the correct cam profile, and makes a visible difference to the smooth action of the machine. The setup looks horrible but actually it went better than I expected, just needing steady hands on the rotary table handwheel to get a satisfactory finish.

 

[Brian-in-Oz]

Hi Charles,
I did an almost identical setup for my master cam follower except that I used 1/2" steel plates for the jig and ground the follower on a flat bed grinder by rocking the pivoted top plate holding the follower to and fro giving a typically nice ground finish. I have not yet tried to grind a test lobe as I have been sidetracked with other activities but should get to it soon. When I do I will post some photo's.
Cheers Brian.

 

[Brian-in-Oz]

Hi all - well I finally got around to see if my cam grinder would work and all looks promising. I made a master cam from aluminium (just a made up profile for test purposes) and ground a 1/4 size cam from mild steel. Now that I know that it works I will do some tinkering around the edges to try and make it a more complete package. The micrometer adjustment for feeding the grinding wheel worked fine but I also think adding a micrometer adjustment to the cam follower would be a worthwhile addition as it would allow grinding the cam a tiny bit oversize and then finish with a final grind to exact size. This would also be useful
in compensating for any grinding wheel wear that occurred when grinding a lobe.
A coolant spray could also be a worthwhile addition at the expense of making the grinding process a deal messier. I will post improvements - additions as things progress and start looking for plans for an engine with as many cams as possible.
I may also post a movie of it working in the future. Some photo's below. Cam is 1/2" base to nose.

Cheers Brian woohoo1

 

[gbritnell]

Hi Brian,
The cam lobe looks great. Congrats on a fine piece of home engineering.
gbritnell

 

[Shipdisturber]

Right on Brian beautiful job looks very professional. Thanks for getting my mind working I have already dreamed up a simpler machine so when the time comes I'll post my work.

 

[Brian-in-Oz]

Hi George and Shipdisturber. Thank you for your kind words of support.I am still tinkering around the edges and have added a micrometer adjustment to the cam follower to accurately dial in finishing dimensions of the cam lobe. This addition while not absolutely essential should add to ease of use. (I just don't seem to be able to leave well enough alone and keep adding incremental improvements).
I will add a photo ASAP. Looking forward to your post and see what you come up with Shipdisturber. This must be one of the best "Heath Robinson" projects to tackle.

Cheers Brian

 

[Brian-in-Oz]

Hi all - here are the photo's of the adjuster I have added to the cam follower.
It is graduated in imperial so that four increments on the dial will move the grinding head 1 thou". The adjuster on the left lowers the rocking arm with the cam follower adjuster locked in place after initial setup until the lobe grind is complete. By grinding the lobe slightly oversize it can be measured with a micrometer and the finishing grind to size easily and accurately dialled in with the cam follower adjuster.
Enjoy the photo's.

Cheers Brian - and a very Merry Christmas and a safe, happy and prosperous New Year to all and may Santa bring each and every one of you a new CNC Mill.*beer*