Best speed for power sanding

[Sturdee]

I'm about to adapt and install my old 5 speed drill press with a flexible hose for power sanding at the lathe. As it doesn't have variable speed changes but only belt changes it is not easy to change the speed once installed.

So what is the best speed to use for sanding.


Peter.

[dai sensei]

Depends on the piece dia, but I have mine at 900 up to 100mm items, even slower for larger ones

[rsser]

With faceplate pieces on the VS lathe, a couple of notches below the speed of the last cuts.

Is that helpful Peter? :wink:

Nah, not so fast that the abrasive just skips over the surface and generates destuctive heat. Not so slow that I'm there'll all day and/or getting distinct scratch marks.

[TTIT]

I have the lathe at around 300 to 500r.p.m and the drill at the point just before the motor starts to whine like a constipated banshee - one of those real quality drills - $25 at Bunnings :B:B That was a big help then eh?! :U

[hughie]

Nah, not so fast that the abrasive just skips over the surface and generates destructive heat. Not so slow that I'm there'll all day and/or getting distinct scratch marks
I kinda go along with this and Vern's thoughts, but it does vary somewhat as what your sanding and so on. There really isn't any great formula or set of rules other than common sense.

[John Lucas]

I agree with the others. I can't give you a number. I turn the speed of the bowl down quite a bit, maybe 500 to 800 rpm. Then I run the drill faster but not fast enough to get the sandpaper hot. I feel like heat and speed are the enemy of good sanding. I try to let the paper do the cutting. Wish I could give you numbers but I can't see the readout on my lathe and my drill doesn't have any readouts so it's all just a guess.

[Texian]

Lathe at 150 rpm, drill about 1/2 to 2/3 which is maybe 600-800 rpm. Higher speeds with light pressure seem to lessen the sanding scratches, especially with the coarser grades. Sometimes stop the lathe to work on the bad spots, but then go over it at speed with lathe turning.

[Hardenfast]

I'm about to adapt and install my old 5 speed drill press with a flexible hose for power sanding at the lathe.

Gents, forgive my ignorance in the substance of this thread, but exactly how does a drill press work in conjunction with a lathe for sanding? Obviously I'm missing some fundamentals in my whole turning basics.

Wayne

[brendan stemp]

Gents, forgive my ignorance in the substance of this thread, but exactly how does a drill press work in conjunction with a lathe for sanding? Obviously I'm missing some fundamentals in my whole turning basics.

Wayne

I think he means a flexible drive. One end connected to the drill press and the other has a sanding disc attached. Quite a good option, I did this many years ago before I got my angle drill.

I think the most important thing is the speed the wood is rotating rather than the speed of the drill. I like to sand slowly except when using a inertia sander, so I would tend to go with the middle speed on the drill press and keep the lathe speed slowish (500 - 1000 rpm depending on the size of the wood.)

[turnerted]

Hi
Using a drill press seems a complicated way of sanding . As ttit indicated you can buy drills dirt cheap nowdays . Allso the sanding works best when you run the drill in reverse . Not sure if you could do this if you are powering it from a drillpress .
I usually run the lathe at minimum speed, about 250rpm and the drill about 2/3power .

Ted

[Sturdee]

Thanks guys for the input.

The reason why I want to use a drill press rather than a hand held drill for power sanding is that I already have the old 5 speed drill press. It has been languishing under the house stored away for a rainy day after I bought a better drill press a year ago.

I also have a flexible drive that fits in the the drill press. Had it for about 15 years and only used occasionally for drilling in tight spots. It has a proper chuck that allows all the normal sanding pads and drill bits to be used and it has a comfortable handle as well.

I also have a space behind the lathe where the unit can go. All I need to do is shorten the central pillar to make it fit. However changing the belts will be a bit awkward so I think I'll start of with 600rpm ( the lowest) and see how it will go.

Peter.

[NeilS]

Hi
Using a drill press seems a complicated way of sanding . As ttit indicated you can buy drills dirt cheap nowdays . Allso the sanding works best when you run the drill in reverse . Not sure if you could do this if you are powering it from a drillpress .


One advantage of using a drill press (or similar power drive) is that it runs much quieter than a hand drill. A significant factor if you are sanding day after day.

Flexible shafts have next to no weight and cause less fatigue after long sanding sessions. Something I appreciate.

All the power drills I have used jet blast fine dust away from dust collection hoods, including towards your head increasing the risk of it penetrating dust masks. Flexible shafts that put the power source at a distance from the sanding zone eliminate this effect.

Isn't it possible to figure eight the drive belt on a drill press to reverse the direction? Wouldn't be a solution for Sturdee who won't have ready access to his the way he is going to set it up and not anywhere as convenient as just pressing a button.

Is anyone using a power drive other than hand drills or drill presses?

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[rsser]

I had a look at air tools, in order to get the benefit of a 45* angle head drill. Only wrinkle is that this tool needs a lot of compressor capacity and so is big bikkies.

[robo hippy]

For me, and my warped bowls, I have the lathe at about 15 to 20 rpm. No way I can keep a sander on warped bowls at anything near 50 rpm. Fortunately, I have a 3 phase motor and converter that I had programmed to run that slow. My old PM 3520A lathe would do that, but the company upped the minimum speed to 50 rpm.

As for the sander, I use an angle drill, not the right angle drill, but the close quarters type that is more like 60 degrees or so. A bit better for getting all the way down inside the bowl. I have slow and high speed models, and mostly use the slow speed ones. I like the drill speed to be in the 600 to 900 rpm range. The slower disc speeds just do a better job. Too high of a speed and the disc does seem to bounce around more, and skip spots. You can reduce the heat problem with less pressure, but at the slower speeds, the weight of the drill is enough.

There was an article on Woodturning Design, one of our turning mags here, about some one who did high speed sanding with a Makita drill that runs at about 10,000 rpm, but he slowed it down to about 6,000. The idea is to just brush the surface. Well, I dug out one of my high speed drills (3200 rpm) and tried out high speeds. It does work, but.... On bowls with a sharp transition area inside the bowl (closer to a right angle, or a small radius) it wants to grab and skip. On flatter curves, it does fairly well. Because I was used to more pressure on the drill, I did have a few heat problems, mostly on the discs, and not on the wood. It does throw the dust out more than slower speeds. It does do the job a bit faster, maybe. I will stick to slower speeds, but a bit faster than I used to use, which was in the 600 and less rpm.

I have one pneumatic drill that I used for a while, and it kept the compressor running non stop. The angle drills are a lot cheaper to run.

robo hippy

[rsser]

Yeah, I'd prefer a 45* or so angled head but there isn't one on the market here in Aus in 240v. A Milwaukee is made in it but not distributed here.

[Sturdee]

Solved the problem with changing speeds.

With the drill press in it's proposed spot the belt cover could'nt open fully and it was facing the wrong way as well. Dug out the old manual ( I do keep them all in a folder :D ) and was able to work out how to remove the belt cover so access to the belts is now possible.

Another question, why do you need to reverse the direction of the motor, I thought that the direction mattered little.

If the direction is important is it possible to install a switch to change polarity to run the universal motor in reverse.


Peter.

[rsser]

Sometimes difficult grain responds to a change in direction Peter.

But you can switch to the other side of the pad to change direction.

That can cause difficulties though at a bowl rim where it's best to have the sanding pad running from wood to air to avoid dubbing over the edge if you don't want that.

[brendan stemp]

Yeah, I agree with Ern. It ain't essential to sand in reverse and if you can't then don't worry. Sanding in reverse can unwind the chuck.

[turnerted]

Peter
To get the maximum sanding effect , the cutting edge of the sanding disc needs to be rotating in the reverse direction to the lathe direction . This may vary depending on whether you are sanding on the near side or the far side of the bowl . You can live with this limitation it's just nice to have options .
Ted

[NeilS]

I had a look at air tools, in order to get the benefit of a 45* angle head drill. Only wrinkle is that this tool needs a lot of compressor capacity and so is big bikkies.

Yeah, often looked at those neat little air tool hand pieces myself, but the thought of a compressor pounding away constantly doesn't appeal.



To get the maximum sanding effect , the cutting edge of the sanding disc needs to be rotating in the reverse direction to the lathe direction .


If you run the lathe in reverse on alternate grits, then the ability to reverse the sander direction is essential to maintain the sanding action outlined by Ted . I don't bother reversing the direction of the lathe having never found it to make that much difference, but I do frequently reverse the direction of rotation on the sander to optimise the angle of approach to the multiple facets on a piece.

Contrary to most others, I run my sanding head at full speed (about 3000rpm) and my lathe at the same speed that I completed the the finishing cuts on the piece (eg about 1000 to 1500rpm on a 12" bowl). I don't find the abrasive getting noticeably hot.... not surprising given the fact that in every revolution the abrasive is spending the majority of the time spinning free in the air. But, I do use a light touch.

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[Sturdee]

I agree that it is a nice feature to have, although I can't run my lathe in reverse so it is not really necessary.

Spoke to my retired sparky mate yesterday and he said that it is possible to wire it up so I can change direction as he learned it in his first year of apprenticeship many years ago. He is going to look up his old notes and see if he can still do it.

There is also a book on small electric motors in my library that I have placed a reservation on that may guide us on how to do it.

This possible modification of the drill press is not really urgent as I'm only getting into power sanding, having only recently started turning bowls, meanwhile I can use a drill if needed.


Peter.

[Frank&Earnest]

My setup, copied from Vern, is a flexible shaft powered by an ancient hand drill fixed in an ancient drill press stand no longer working, set on the lowest of the 2 only speeds. I do not worry about that speed because I can always vary the lathe's speed to find the best combination.

Re sanding in reverse. Last weekend I saw Tim Skilton demonstrate it by using the reverse switch on his lathe. He said that just by screwing on the chuck a bit harder with a final bump he never had problems with the chuck unscrewing. His reason for reversing was not so much for getting a better sanding, just to send the dust towards the chute instead of towards himself.

Given that I do not have a reverse swhich but the headstock can be swiveled around, can anybody see any problems with doing it like that, besides having the on/off swich at the back? Haven't tried yet.

[Sturdee]

M
Given that I do not have a reverse swhich but the headstock can be swiveled around, can anybody see any problems with doing it like that, besides having the on/off swich at the back? Haven't tried yet.

I can't see any problems except that access to the on/off switch is not easy in an emergency. I would wire in a kill switch located in a convenient position at the front of the lathe in the power circuit to the lathe.

I got a large architrave light switch from Bunnings for $ 10 for that purpose.


Peter.

[Frank&Earnest]

Thanks Peter. A knee kill switch is a good idea regardless of the reversing, that may be the way to go. Which rises another question: at that point it might be worth installing a reverse switch also, which saves the trouble of swiveling the head but leaves the problem of the possibility of unscrewing the chuck. Tim and Brendan seem to value this option differently. Can we have a straw poll? :wink:

[NeilS]

I like the controls on my current lathe which can be moved to any preferred location.... which is always within reach so I don't have to move into the firing line to hit the stop button.

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